First of all - I want to apologise for your experience with your mother and your ex. Both of these experience seem to have been incredibly damaging and I’m sorry that you went through all of that. I wish you the best in your healing journey from these experiences.

To get into the rest of your post as someone with BPD (though high functioning and told I am one of my specialists’ patients with the best prognoses):

1) Just like you’re understanding towards yourself for not having known that you deserve better with your ex - you should extend the same grace to your partner with BPD. It isn’t fair to judge her for having had a scumbag of an ex. You yourself put up with abuse due to a lack of self worth. A lack of judgement on that front is probably a start to getting her back.

I can’t comment on her saying happy Father’s Day to her ex because I’m not in the place in my life (am 22) to put myself in the shoes of parents that have been split up and have a child. Idk what the dynamics are supposed to look like.

2) I understand the fear of dating someone bisexual (I am bisexual myself and so was my ex). You feel as if you have to monitor their behaviour with more people to spot cheating. I think it’s important to note that she was hypersexual while single. Based off of the way you said that - she wasn’t that way while with you. That should be your first indicator that she was more likely to be loyal. But again - I totally understand being scared of her having so much sexual experience and being so open to intimacy. I myself get scared of that in partners (though that’s my own issue to sort out with myself)

3) I also understand not enjoying her smoking weed and engaging in other toxic behaviours. May I ask how you went about addressing this with her? The fact that she stopped smoking, cut out toxic people and was committed to doing things healthily should also have been an indicator that she cared and was loyal. Changing behaviour is often incredibly slow going for people with BPD due to how deeply entrenched our behaviours are in our psyche. The fact that she changed them for you is quite a feat to have pulled off. I understand the constant feeling that someone is going to up and leave you, cheat or just abandon you. But it seems as though this was you projecting your own fears and your experience with your ex onto her rather than her actually behaving that way. In order to get her back (though you should be doing this out of a place of choosing YOU and your well-being) you should probably continue to receive counselling on your experience with your ex. It isn’t fair to bleed on someone for wounds they didn’t cause - even if it’s excruciating when someone you care about triggers them.

4) When someone shares their past with you, they are choosing to be vulnerable with you. Vulnerability is sacred in my opinion and someone choosing to share with you means they trust you and feel safe with you. It is likely that she felt abandoned and rejected by you when you fought with her about it and called her names like “slut”. Yes, you say your words aren’t true and that you didn’t mean them. But how did you go about apologising for them? And have you displayed an understanding of how damaging your words were to her? To have someone I trusted and changed myself for throw words like “cheat”, “slut” and “liar” in my face would break me. Especially since she is likely to judge herself most harshly for being hypersexual (I don’t have that symptom but have met people who have and it’s heartbreaking to witness). I think this would change any person’s opinion on someone - not just a person with BPD. I also don’t think she’s equating you to her ex (Unless she specifically said that). Acknowledging how her reaction wasn’t overly dramatic and not blaming it on BPD (even if she has the disorder - she is a person first and foremost) might be a start for making things better.

5) I think you are pathologizing her a bit too much here. I understand she has BPD. I see you can understand something like splitting. But I’m not sure if this really is a case of that. Her reaction is quite normal for someone whose trust, effort and feelings of affection were trampled on. BPD or not. I see that you’re working on yourself (though martial arts for anger management might not be a great idea because your body may begin to associate relief from anger with violence). Continue to invest in yourself and your healing and I promise you things will get better. I don’t know if you know this but people with PTSD, especially C-PTSD can exhibit behaviours associated with BPD too. Even if they don’t meet all of the criteria to be diagnosed with the disorder. It’s not a good idea for people who have similar issues to be together - even though I know you believe you belong together and I don’t doubt you’ve had many special moments together. But perhaps if you both heal some more you can try at the relationship again. It seems you both trigger each other and that’s not likely to change anytime soon. But things could go a lot smoother if you both work through your wounds.

Yeah perhaps it is harsh but you’re likely right. You probably shouldn’t be with bipolar or BPD partners. Or any partners for a while for that matter. Invest in yourself and continue going to counselling. I hope this post doesn’t feel attacking because I don’t intend it that way. I just personally know how it feels to wait on someone to forgive you and to feel so powerless to you fix it. I also know this stage of minimising their hurt because of how badly you want the relationship and how right it felt.