Hi SurvivingBPDex,

I'm happy to hear that you're choosing to do work in therapy, it can do wonders with a good therapist. My advice to you if this your first T, make sure that they gel with you, you don't to settle with the first T that you find.
The next part is easier said than done, shift your focus away from him if you've exited the r/s and focus on yourself. I suggest to do a lot of self care, what do you for self care? Use as many resources that are available for you, you're going to a T, use this board to process the grief with people that have been there, do you have a supportive friend or family member that is non judgmental and a good listener?
Make a chiice with your boundaries, and I mean self protection, do you want to go NC ( No Contact ) or MC ( Minimal Contact )? I strongly suggest that you self protect to give yourself the adequate time and space to mend your wounds because if you don't you're exposing yourself to harm by having your ex reopen your wounds, it can feel like one step forward and two steps back when you engage your ex by taking the bait or JADE'ing. Its also good practice with boundaries if you didn't have a lot of boundaries or you had floating boundaries. I canot stress this enough keep defending your boundaries at the onset protection, it will get easier.
My last bit of advice to you is don't look too far ahead, take it one day at a time and break that down even further, take in one hour at a time if you need to. Hang in there.