Questions: Break Up & Divorce

Maybe an ex that cheated?

My ex and I broke up in January cause this old client of mine popped up on tiktok as one of my friends still, that I had priorly lied to her about snapchatting. I was committed to my ex and in December had gone on a trip with her that cost $3500. I was going to move in after the vacation but she broke up with me again. She tried getting back with me but i didn't want to just yet because she wasn't forgiving me for everything and kept bringing it up. I thought moving in would end us completely. We've talked everyday since and have hooked up and in February she said she went on a date with someone. Nothing came of it but I could tell she kind of had a thing for him. We continued to talk and go out to eat and hooked up once. I thought we were going to get back together. Just recently, in the middle of May I asked her to grab dinner and she said she was seeing someone. Totally blindsided me and now Im destroyed and can't sleep and eat. She said "I wanted to let you know cause you said you didn't want to talk to me if I was talking with someone" A week later I called her and begged for her back but she told me to move on and that I would find someone. She told me things were serious with him and that he met her stepdad that raised her, went over to her dying fathers house but didn't meet him and met one of her friends. She told my mom that they were moving very very slow and he was the one that wanted to meet everyone. She has abandonment issues and I'm afraid that these guys will be together forever, cause he hasn't been in a relationship in awhile either. He doesn't mind that she still talks with me but I'm on day 7 of not contacting her at all after my mental breakdown phonecall. I want my ex back and I don't know what to do to make her trust and forgive me again and show her that I'm committed. Opinions? I am A, the new guy is B.