ex-gf(uBPD) back together with infidelity partner

[chapter100]

I first posted here back in late 2016.  My girlfriend and I were in a long distance relationship and I was few weeks away from moving across the country to be with her.  After I'd sold most of what I owned and gave up my apartment, she cheated on me and asked me not to move.  She dated her cheating partner for three months before we reconciled.

I moved in January last year and although we had some rough moments, most of 2017 was great.  In November things went from going well to her realization that she's treated me badly, treated everyone she's ever dated badly, and even treated her cheating partner badly when they were together - she said she only dated him out of guilt over the affair, and that since she just disappeared on him that she she should talk to him and give him "closure".  The day after that she decided we can never see each other again as it would be the only way for her to stop hurting me.

Now it's February and I confirmed through Instagram that she now in a relationship with her cheating partner for a second time.  I feared this but I didn't really want to believe it was possible.  I'm still in disbelief - I'm literally having trouble accepting it's all real even though I have seen the photographic evidence of it.  I am so deeply brokenhearted and hurt by this betrayal that I can't sleep, I can't eat, I am overwhelmed with anxiety, and profoundly humiliated.

Everyone I know, including my therapist, wants me to look at this fresh round of pain as a catalyst to abandon this person permanently, but I can't do it.  I need her back and having her not only be gone but to be involved with this specific man is destroying me.

[RELATIONSHIP PROBLEM SOLVING]

RELATIONSHIP PROBLEM SOLVING This is a high level discussion board for solving ongoing, day-to-day relationship conflicts. Members are welcomed to express frustration but must seek constructive solutions to problems. This is not a place for relationship "stay" or "leave" discussions. Please read the specific guidelines for this group.

[randomuser94]

Those relations are like drugs.
I've been with my ex 2 and half years and got dumped 3 times for "lets take a break" to actually try other partners 2 days later. we broke up the 3rd time almost 2 months ago
  I've never been so confused in my life. With me she talks how she wants me back in the house(but can't because she is ashamed of how everyone thinks of me-because of her painting me black everywhere), how much she loves me etc while with her friends she talks about "the monster I am. She tells me she won't move with anyone, for a while but I've found out she asked 2 guys already(1 is about to move with her).
  I'm so confused whether our love was real or not. And the biggest pain comes from the fact that I can't manage to let go of my feelings. It's not easy to leave someone you love that keeps telling you that she wants you back.
  I know my only solution is No Contact and delete every way of contacting her... when the pain will be too much for me maybe I will have the power to stop this
 

[chapter100]

  I know my only solution is No Contact and delete every way of contacting her... when the pain will be too much for me maybe I will have the power to stop this
 

I'm sorry you're going through this and of course I can relate.  I can't bring myself to cut off my ex's means of contacting me if she chooses, even though the pain she is causing me is so deep that I fear another hospitalization is in my future.