Feeling Worthless--A Venting (Possible Trigger?)

This has been a really difficult post to write. I am just taking contrary action so that no matter how much something hurts, I have to get it out so I will hopefully feel better. Lately I hit an emotional rock bottom. It didn't help that I gained 40 pounds in 5 months, but I noticed a pattern in myself. All my life, I've been made to feel worthless, both from my dad at home and from the kids and teachers at school (I have the learning disability ADHD as well so before I was medicated, everyone assumed I was stupid). I desperately began seeking things to make me feel worthwhile, but everything I tried was met with failure. I suppose this wasn't unusual but though I didn't realize it at the time, I began to attach self-worth to whether boys (and girls) liked me. I was very promiscuous in my past and I think it was because I attached my self-worth to whether people would sleep with me or not. Over this past year I fell hard for someone and was completely monogamous with him and was very happy. He broke it off with me some months ago, (which crushed me) explaining that now was not the time for a relationship. The problem with that is I have a head that keeps telling me how worthless and ugly I am, especially since I gained this extra weight. We're still best friends but I miss being in a relationship with him and all the things that go with it (yes, I am also talking about sex). I feel worthless ironically because of my past behavior. I feel ashamed because my desire to sleep with him has never waned. It's not just the sex either because I am still very much in love with him. I still feel guilty for wanting sex period. I keep wondering what he must think of me and how disgusted he is by me. I bet he doesn't even believe me when I say I want him not just out of pure lust. I guess I have to keep telling my sick brain over and over again to shut up...that he wouldn't have anything to do with me, be it friendship or otherwise if he was completely disgusted by me in every way. I am ashamed of being sick. Logically, I know that's retarded. I feel like there's no hope for me...that I'm going to be sick forever and my relationships with people (be them friendship or romantic) are going to be ###$ up for the rest of my life. Sorry if this has been so depressing, but I have been holding this in for months now. Can anyone relate?