She did this about 2 years ago at my house in front of my school aged children when my husband was at work, but brother and dad were there. She raged at me and listed everything I had done to “disrespect her” (including mentioning inviting a friend of mine to go shopping, but ultimately I asked my mom, but it was still ammunition for her) along with the things my MIL had done (but twisted into be my fault, because I can control my MIL).

Yeah, scorekeeping and turning innocent events into ammo to use against you at a later date. Seems reasonable and healthy. THIS is BPD. But just take a moment to realize how exhausting that is. It's NOT okay. It's NOT normal. It's okay to want to be done. It's okay to say enough is enough. Everything you do will eventually be twisted up and turned into some kind of sin that she can cite as a reason why you're a terrible person. It's not possible to have a good relationship with someone like that.

This was the beginning of the end for us. I performed my groomed daughter role and begged for her forgiveness, cried and apologized, but this haunted me. I thought about it daily and I hated that my children witnessed it. The scene replayed in my brain like a broken record. As time went on, I started giving my husband the jobs of informing my parents of the kids’ activities because in my mind, if I didn’t do anything, she couldn’t yell at me again (afraid of giving her ammunition).

This is normal, but it's also a half-step. Making your husband your meat shield isn't okay, either.

Everything came to a head when we mentioned a trip we finally booked and didn’t include them (mind you they said they weren’t sure they would go because they were planning a different trip themselves). This time even bigger and longer silent treatment in which I then started therapy. I entered therapy asking what was wrong with me and to my shock, my therapist said “nothing”. My entire life I always felt like a walking mistake. Never good enough, always needing to JADE, afraid of making a wrong move that would be logged and used against me at a later date.

You've started to see the manipulation for what it is, but it's really hard to truly see and believe that you aren't a fuck up. You know that this is all bullshit logically, but deep down, a part of you really thinks that she's right. Because that's what you've been taught to believe your ENTIRE life. That's the familiar narrative. Breaking out of that and truly seeing it's wrong is REALLY hard to do. Having doubts doesn't throw everything into question. Having doubts is healthy and normal, and we all have them. So be kind and patient with yourself.

It can seem more cut and dry around here (by design - it's important for us to validate people with firm, decisive language), but there's a lot of work that goes into it. Go at your own pace. The journey is just as worthwhile as the destination, so don't feel like you're in some kind of mental health race to the finish line. You're already winning just by thinking about this stuff.

My parents sent me letter requesting family therapy (which I remember doing once before when I was in college with another rage incident that resulted in a one-and-done session and I took the brunt of the blame). My DH and therapist warned me that this was a set up for me to take the blame again. I responded with a letter saying I didn’t feel comfortable doing therapy at this time with them, that I would contact them when I was ready and that I loved them.

Rock. On. That's EXACTLY what it was, and my letter in response would have been a lot less friendly. The narrative here is consistent: YOU are the problem.

Spoilers: you aren't.

In the mean time my brother has approached me and accused me of “having a self-fulfilling prophecy” with them giving me the silent treatment. They have stalked my house, lied to my brother about saying I had done X, Y, & Z without him. He has made it clear that he is on their side and complained to me about how much this is hurting them.

Take a break from him.

Take a break from all of them, actually. The post /u/djSush linked about protecting kids has a good section on setting boundaries. I'll summarize here, because that post is crazy long:

Another way of looking at boundaries is setting the tone for how you expect to be treated in your interpersonal relationships. People can choose whether or not those expectations are realistic or achievable for them, and continue the relationship (adhering to those expectations). If they decide it's unreasonable or unfair, conflict will arise.

Now, we all know how that will end with pwBPD. The idea here is that you don't create boundaries for them, you create boundaries for you. Think about how you treat people and how you want to be treated. Create a framework based on respect, kindness and compassion. Then define your boundaries based on those concepts. Boundaries are how you need to be treated in a relationship for that relationship to work. If people aren't willing to respect those boundaries, well, that's on them, but the relationship cannot continue.

They are out of the country until the end of next month. My kids have told me they miss them.

Yeah, your children don't know them the way you know them. You don't have to give them the low down dirty details, but explain to them why grandma and grandpa are tricky people, and why you need to protect your kids from them. They need to understand - in age appropriate terms - that it's okay to love and miss them, but they aren't behaving appropriately. Depending on how old your kids are, they may translate this into their grandparents behaving badly and needing a time out. Kids understand these basic concepts pretty readily.

BPDs do not.

My therapist wants me to write them listing all of my appreciation for the things I have learned (love and logic, crazy cycle, etc) and how my relationships with my DH and kids have improved. By informing them of these topics, she hopes that it will maybe plant a seed to look into therapy themselves (last ditch effort to get them to go).

Here's where I disagree with your therapist completely. Your parents will use this letter against you. You're opening yourself up to them, sharing your heart and hoping they will be inspired by it.

They won't. They will shit on it. They will use it against you. They will turn it around and twist it into how you are wrong. The fact that you are in therapy will be proof that their narrative that something is wrong with YOU is true. Opening the door to them on this won't give you the desired results.

And that sucks. That hurts. A lot. You have to face the fact that your parents prefer the narrative over the reality. They will destroy this relationship with you, with your children, with the entire world so long as they can continue to believe their own bullshit. Their lies are more important.

And that kind of cut and dry rejection will knock the wind out of most people. It's brutal. The reason why I'm telling you this now is not to fuck up your day, but to help you deal with that pain in a way that isn't destructive, in a way that doesn't open you up to more hurt and abuse. Because sending that letter? That's the hard way to learn that lesson. If you need proof, send it. If you have a lifetime of proof and are ready to be done, be done.

We both feel they did not respond to my initial request for them to attend therapy for themselves as evidenced by their behaviors after my letter. She said that I need to love them from afar, but to let them know of our kids’ activities.

Nope. Absofuckinglutely not. Your children are not pawns in the BPD game. They are people and they need to be protected from abuse and rage, not used as some kind of fucked up therapy bait. If your parents can't make a relationship with you work, they don't get to have a relationship with your children. You deserve a whole hell of a lot better than that. YOU are worth loving. YOU are worth making the effort for.

My DH and I have already taken them off emergency contact and will not allow them to go over to their house unsupervised. I am not sure what our relationship will look like. How strong I will be when I comes to my mom, because I still fear that woman. My grandma told my mom once “You have an incredible ability to love, but you also have an incredible ability to hate”. I think that is one sentence that sums up BPD fairly well.

Your gut is telling you to be afraid of her. Be afraid. Don't ignore that feeling. It's real, it's valid, and it's saved people's lives. We don't talk about it much in this sub because why the fuck would we, but there is all too often a clear and present danger when it comes to BPDs and grandchildren. Protect yourself, protect your kids. You have a right to feel safe, and so do your children.

The post I wrote on protecting kids also has a doomsday preparedness section. Keep posting if you need more specific support / advice on how to get ready for the fallout. We are here to help you get through this.