I'm obsessed with my looks?

Some dear people to me say I'm good-looking girl and that i could be a model, but I don't believe them. When I look myself in the mirror all I see is ugly. I stopped going out, nobody even calls me anymore, I've lost most of my friends. I'm just very aware of my appearance as negative and people don't like to be around me.
Most boys usually tell me I'm ugly, some say I'm pretty but I trust no one. My ex told me I'm pretty but he said to me that he is the only one who sees that and that people around him say that I'm ugly. That was a reason we broke up... i'm constantly asking people if I'm pretty and I'm always seeking for some social validation, but all I see is ugly. Sometimes I don't see myself as ugly, I actually like what I see, but it lasts for only like a second... i'm so alone, I'm so nervous I even experienced few breakdowns past few years. I think about plastic surgeries every day, and every second... I just can't afford it, when i have a job I usually spend all money on makeup and clothes and I don't get a lot of money. I left collage and I ruined my life and I don't wanna live anymore. All I feel is a deep pain in my chest.