I see myself as a useless gray lump,

I've been out of work for about a year and a half now, and that's making me feel bad about myself. In addition, I found out this week that two friends who I haven't seen in a few years are getting married, and I'm not invited. I'm assuming this is because we haven't talked in a few years. I'm always afraid to call friends and people, because I assume I'm a nuisance and annoying them, because why would they want to talk to me? Does anyone have any tips on how to improve self-image?