There is nothing wrong with you, but sounds like you aren't finding true friends. I've found most people to be incredebly self centered. Also, life for some just moves so fast they don't take the time to be good friends. I think some have forgotten what it means, even. You may feel lonely but you are certainly not useless. We are here for a reason, but I can't figure out what my reason is either. I've had the same thoughts as you about ending it all, but something keeps telling things may get better. I'm depressed if you haven't already figured that out. I struggle daily with it. I, too, have medical problems that make me even feel worse. But I keep going for what little family I have left with the hopes of making a few more memories.

Keep fighting. There are good people on here that are willing to listen and be friends. And don't give up on the outside world. A new real friend may be right around the next corner for you.