Hi Kit Kat
I don't know if this will help you and you received some good advice already so feel free to ignore me if it doesn't feel right to you!
But I wanted to reply because what you said about obsessive thoughts and not being able to stop thinking about someone even though you want to is something I very much identify with - I've had this problem with one person in particular.
I don't know why but something about your situation seems very familiar in this case. For me, it was a friendship which almost developed into something more but it never did because, although I didn't know anything about empaths back then I did sense that I needed to try and keep some firm boundaries between us because of the many issues he's had to deal with in his life. For a really long time I held onto the idea that we still had a friendship because I could not accept that maybe this person was taking advantage of my good nature - not because he's a bad person or anything but very damaged which as I'm sure you know can result in some hurtful behaviour.
Eventually I did have to come to accept that this friendship wasn't healthy, and that even if the hurtful things he did were unintentional, and even though I really wanted to be a good friend and be there for him, all that was happening was he made me feel crappy about myself and he used me to dump all his shit on and feel better about himself (though I do think this was mostly unconscious.)
Anyway, even just accepting that was HARD. Cutting him out of my life was even harder, and I went through a difficult phase of thinking about him a lot and feeling incredibly guilty and worrying I'd done the wrong thing and wondering if I should cave and try to find some way to reach out to him. But I also knew that a lot of what I was feeling was fear (and I think some of that fear was also his, because he had known he could always rely on me for so long and now he suddenly couldn't). But I had thought really long and hard about severing the links between us and why I should do it, and I felt deep down it was the right decision. Even though I miss him, I know now this was the right decision. I am so much happier now without this toxic relationship skewing my perceptions of a lot of things, including myself. It also helped me to realise some really important things about myself and learn some lessons I probably should have learned a while ago! But overall it has been a difficult but positive experience and I feel more like myself, and like a better person, because I listened to my instincts about this. So the reason I told you that long story about me is because I think the situations are a little similar and what helped me most was:
Cutting cords - it was hard but it made a huge difference. I had to do this more than once and actually it helped me to accept that a part of me was afraid to let go - I needed to acknowledge those feelings before I was really ready to move on.
Reminding myself (a lot!) Why I made this decision and why it would be better for everyone in the long run.
Being patient with myself for taking a long time to get over it and stop obsessively thinking about it all the time - and remembering that some of what I was feeling was headed my way from his direction too, although again I don't think it was intentional.
As I said, I still miss him and think about him sometimes, but I don't feel guilty or blame myself anymore. We both made mistakes and now we can both move on hopefully to a brighter future even if we didn't end up close friends like I wished.
Obviously your situation is different and unique to you, but if any of that is helpful or makes you feel better then please take away whatever is useful
Sending you some happy vibes xx hope things get a little easier xx