Boozle,
Welcome to the forum, I'm very sorry to hear about what you're going through. It's happened to all of us here at some point. Try to focus on yourself and make your needs a priority.
I saw where you mentioned seeing your ex flaunting her new relationship on social media. That happened to me, and I'm going to briefly share what I experienced and what I ultimately had to do to preserve my mental health. My uPBD ex-g/f of nearly two years wanted an engagement/marriage. She gave me an ultimatum early last April saying "either we get engaged or I'm out. I can't live like this." I couldn't proceed until she worked out her mental health issues, but said I would stand with her while she did that and assured her that I loved her. We talked on and off for about two weeks on how to work things out. The last time we talked on the phone, she asked me to contact her in a couple of days. I sent her a text on a Friday night asking her if I could call. She sent me a text the next morning rubbing it in my face that she had been out on a car date with her old friend from high school. This guy was the twin brother to her high school b/f and the guy she rebounded with after she left her ex-husband about 3 years ago. Hearing this from her literally destroyed me emotionally. When she told me all of this, I got the impression that she flat out didn't give a
PLEASE READ.
A week or so after the initial hookup with him, she's on social media describing their dates, where they're going, posting photos, etc. Roughly two weeks after that, she's professing the relationship and changes her profile picture to a picture of him and her together. Seeing this nonsense daily was literally driving me mad emotionally. I couldn't eat, sleep, and had a tough time going to work each day. I started seeing a therapist right before my ex professed the relationship on social media. The therapist said "You need to remove her from your social media ASAP and don't answer her texts if she messages you. Seeing these things is destroying you emotionally." I told my therapist that I was worried that I would hurt my ex by doing this. My therapist said, "You have to take care of your mental health and worry about yourself instead of her. She obviously isn't too concerned about your feelings at all." I finally bit the bullet and removed her from both of my social media accounts. It was very painful to do that at first, but that's what was ultimately best for me. This might be something you should consider if seeing what she's posting is causing you too much pain.
Typically, people with BPD like to come back for recycles, so please be aware of that. My ex has a pattern of recycling men. As far as I know she's still with this guy, but I have been contacted by her at least 6 times since the breakup and had an in person visit a couple of months ago. The times I've had to acknowledge her, I've kept conversation to a minimum so I don't give her the impression that I'm still interested. Like my therapist said, "Just practice compassion from a distance. Try not to be angry with her because she is mentally ill." I'll admit that I still love her, but I can't go down that road with her again because it will just be more of the same.
Take care of yourself and post as much as you need to. There's always someone here that is glad to listen to you. I've been rambling on in here for several months now getting my feelings out.