I've known this guy for many years, and we dated for about two years.
Whenever I'm with him, I am happy, and now that I've met him, I can't imagine myself with anyone else. I've tried moving on, and it hasn't worked. The last guy I dated, used me and then left me. And then apologized and blocked me.
But this guy is the best thing to happen to me. He's my best friend, and the only one who's seen me at my worst and cared enough to stick around and try to help me. He moved a few years ago, and when he invited me to visit him, of course I jumped on it, but I had, days earlier, started dating the guy I mentioned who used me. I got there fully intending not to tell him, but I felt guilty, and I couldn't continue, and it ruined our reunion. I had an inkling even then that I should go back to my friend, but I did not, because I am an idiot. I tried breaking up with him, and I finally got him out of my life, and immediately I started trying to speak to my friend again. It worked. Kind of. He said he was dealing with anxiety, and do not feel like having guests over at all, but that he was happy to hear from me, and to message him frequently, which I have been. They haven't been as good of conversations as I'd like, but we're always better together in person, but recently he stopped talking to me, and the other day I noticed a girl had tagged him in a life event of a relationship. I did message him and let him know I'm happy for him, because I want him to be happy, and I would never want to guilt trip him into coming back to me.
More than anything, I want him to be happy, and if I can't make him happy, I want him to find someone who does, but I do know I make him very happy. I have been feeling oddly optimistic, like I know eventually it'll work itself out, and we'll be together again, eventually. It's just there, like a little bird on my shoulder telling me it'll work itself out, but my conscious, logical mind is telling me it looks awful and it'll never be corrected.
I know the last time I didn't use my birdie, I let go of my friend for the guy who used me, and I feel this is frequently the case. If I listen to that voice, it usually turns out.

I'm sorry to come here and clog the forum with this, but this is huge to me. I deal with severe depression and anxiety, and I feel so much better when he's around. I can't explain it, he just makes me happier than anything or anyone else. I have few friends and no family. I had a therapist once, and she commented how much happier I am when I've seen him. She wasn't very good so I stopped seeing her, but she did get a few things right.