I'm so sorry you feel like this. I wish I had some good advice, but I really don't. I can say love doesn't magically fix things, though. Intimacy can be disappointing and leave you empty, even if it's nice in the moment. And if you have it and lose it, that's also pain. I can't seem to recover from losing the person I loved most.
People are rarely as unattractive as they think they are. Even traditionally pretty people often think there's something wrong with them. I criticize myself relentlessly, but I don't really judge people around me. Chances are, other people are the same way. And if they are telling you you're ugly, that says a lot about the kind of person they are. Probably not worth your time!
If you really want to give it another shot, I don't think it's ever too late. It's work, though. You can't just hide and hope something finds you. I mean, how many people can you meet if you never leave your house? Maybe you could start small and just start going to places where you'll encounter people with similar interests? Not with the intention of meeting people, so your shyness isn't in the way. But you'd have a better chance of finding someone with something in common, which helps a lot. Looks are not a good foundation, but enjoying something together is.