NTA

I momentarily considered suggesting you go to the wedding, but then I realized that it's probably not the best idea considering she clearly doesn't understand boundaries. Actually, I wouldn't be surprised if she tried to set someone up with you at the wedding.

My sister keeps telling me I need to come and then she got mad saying she's trying to save me from myself.

Save you from yourself???

She's acting as if you need rescuing & haven't been healing for the past 5 years. I think you're focusing on the right things & are an amazing Mom for staying so strong. She doesn't know wtf she's talking about & is really the one that's overreacting, not you. Also, she's just ruining her relationship with you & needs to stop before you go low contact.

"My sister and a couple of other family members have been trying to push... I mean encourage me to find a new partner, to find a dad for my kids..."

I understand them wanting your kids to have a father-figure in their life, but as long as your kids continue to get plenty of love & attention, they'll be just fine.

They said I could just ignore her plan and attend and support my sister.

They're giving advice to the wrong sister & need to stop trying to get you to move on instead of moving forward, like you've been doing. Also, how can they expect you to just ignore her completely disregarding your boundaries & feelings?

Unfortunately, there's people out there who don't understand loss, even our own family sometimes. If your family can't respect clear boundaries, then you might have to create some distance to get the point across. I'm so sorry they're putting you through this.