SO. I’ve been with my boyfriend almost a year, both 29. We have had serious problems throughout with his infidelity. It’s not full blown cheating, we will label it “sleazy social media behaviour” and consistently lying about it. So many fights, so many times he says he will fix it. I know, I’m dumb for believing it would change. He’s also quite controlling and I want to use the word manipulate, and I don’t use it lightly because his therapist has also described his behaviour in this way. Each time an incident occurs, I have an enormous reaction, often resulting in self harm and other problematic behaviours. I hate this life for me and have been working so hard to get my mental health together. I have the support of friends, psychologists, and other professionals. I also have a DBT group I attend weekly. 
However, the most recent issue came about when I found a group chat on his phone, (to clarify, he handed his phone to me to prove he wasn’t talking to another girl,again)) only for me to find a group chat he belonged to rampant with pornography. I had a bpd blackout rage episode.. 
I calmed down, we moved on.. he promised he was going to do anything and everything to make this work between us and he knew what that entailed. He went and saw his therapist and came back saying how horrible he felt about the way he treated me, blah blah blah. 
Then 5 days later while I’m at work he starts on a new narrative, “I’m trying everything I can, I’ve done everything you’ve asked me to do and I still can’t make you happy, I’ve failed you”.... more and more along the lines of trying to push me to break up with him, when that didn’t work he simply said “I’ve done everything I can .. You can’t keep being hurt like this. I’m just gonna go” then I heard nothing else, came home from work and he’s moved all of his stuff out of our apartment. 
I am in absolute shock. Deep down I knew it was highly likely it would end soon if things didn’t rapidly change but to get dumped at work over text and abandoned is .. next level. The other thing is that, he knows one of my exes did this exact thing to me before and I have ptsd over it so it feels like a stab in back. 
I need some urgent DBT style coping skills because getting stoned is my option atm and while that helps for the minute I’m aware it’s not a solution.