This is my first post so I'm sorry if it's not up to par, but here goes nothing.
I'm an 18 year old girl with a lot on her mind. After a 2 year relationship with my second ever FP took a negative turn, I cut all contact with him and blocked him off of all social media. Lasted about 4 months, surprisingly; I found another guy who was very emotionally vulnerable immediately after, and manipulated him into falling in love with me. I hurt him as badly as I could, just to see if I could make him care for me again repeatedly during that timeframe. The game got boring, though, thus driving me back to my ex. At this point in my exes life, he was virtually homeless and hadn't any family he could rely on. I didn't care to spend time with him anymore as I'd find whenever I would, my intense feelings of love mixed with sympathy would drive me to spend too much money on him as a result of his situation. 

Without seeing him irl, I grew bored and began to play with the feelings of any guy who expressed interest in me, and quickly found a new FP in one; the guy who fell in love with me post-breakup with my ex. He had grown to resent me for hurting him so many times, so I'd put great effort into bringing his feelings back and then ignore him for days when he'd express any affection; immediately redirecting my attention to my ex. This went on for 3 months before I was diagnosed with borderline personality disorder. 

The intense feelings of hate I felt for myself originally, about my manipulative tendencies, my impulses and the things that brought me joy, were replaced with understanding and a desire to use this knowledge to better myself. I had to start somewhere, so I ghosted and blocked my ex. He fell for me because he was broken and easily manipulated, used me to feel better about himself, and I felt the only reason I still talked to him was because I wanted his validation when ignoring FP and that was wrong. I told FP the truth about everything; talking to my ex, the reasons why I'd do what I did, the truth behind my manipulations. He was insanely okay with everything and extremely supportive, also stopped flirting with me and started just focusing on being a good friend. He however wasn't familiar with BPD, and had no idea about the fact that I obsessed over him as I really didn't feel comfortable sharing that with him, we have too many mutual acquaintances. 

It's now one month later. Despite the initial positive reaction, over time FP started doing cocaine excessively and making passive aggressive comments towards me every time we talked as a result of all the shit I've put him through, so over time I distanced myself from him. I told him not to talk to me again after one particularly bad fight and the distance I created has made it easy to stay away. I've started seeing someone who is aware of my BPD and familiar with what it means to be with someone with BPD. We're building a fairly healthy relationship thus far, but I'm aware that as I grow closer to him, despite my best efforts it'll be increasingly difficult. I excersize when I start to feel I'm splitting, smoke weed when my negative emotions are extremely strong and sing until my brain stops being dumb when I want to get upset at him over unreasonable things. I don't want to be my BPD. 

At nights I find myself thinking of my ex, however. Tonight is one of the worst since I stopped talking to him initially. I want to stalk him so badly that I had my finger over the unblock button; just to stop and then immediately start writing this. Is it wrong that I want to see if he's okay, and explain to him that I am not well? He did contribute to a lot of the problems in our relationship, but I found out the reasoning behind why I did the things I did, and it wasn't because he let me down and didn't do the things a boyfriend should do. I'm just not sure if telling him that is taking a step backwards; he might've moved on with his life completely. I also question if I was wrong to cut off my old FP because I feel like I broke him down. Some days I feel like I'm doing well; and others I feel like my the hopelessness of my diagnosis is leading me into complete isolation slowly. I can't trust my own judgement at this point and my therapists on vacation, so I decided to write an unnecessarily long text post to distract myself from doing something I may or may not regret and hopefully receive some advice. 

Thanks for reading! I apologize once again for any errors.