  Hi,I've made some terrible mistakes with my ex. I don't know how to fix her or apologize and would appreciate some help.
   
so my ex gf was molested by her uncle at 8. Her younger sister was born and he then started abusing my ex and telling her she wasn't his favorite niece anymore and she was a disappointment, etc. and molesting her sister instead. 

  When I met my ex she didn't show any signs of bpd. Then we got pregnant. Due to medical reasons, the baby ended up being still born. She also hemmorhaged in the hospital and almost died. She began being extremely emotional and started therapy. This is when she was diagnosed with bpd and also ptsd. 

Around this time, I met someone else and left my ex for her. My ex took it horribly. It took a full year for her to obsessively texting.

My gf cheated on me a few months ago and we broke up. This is the part I messed up even worse on. I went back to my bpd ex. She seemed so happy and I thought I was back in love with her again. I thought I wanted to be with again. But the girl who cheated on me came back and apologized and I realized I wasn't over her at all. I broke up with my ex and once again she took it horribly. 

My ex then would show up while I was alone at my apartment in lingerie and such and basically seduce me. I know in the end it was my choice but we started an affair. 

My current gf found out and I'm convinced not to do it again or ever talk to my ex again. But I'm afraid she's going to kill herself. She's threatened it before and I don't think it's entirely for attention. I know I've treated her very badly. I want to know how to make this situation right. Please help me.