Everyone has trials and tribulations in life, but other people having it worse than you doesn't mean your pain is any less real. I think I know how you feel sometimes. I have been there too often. When I feel depressed I isolate myself and shut off the world. It is a strange feeling to be alone in an office full of people, but that is how I feel at time. I don't think you are incapable of being loved. I think there may be someone out there who can love you, but I think you need to work on loving yourself. It is an issue I struggle with as well. Sometimes I have such low self image I think my wife doesn't love me anymore. It's not anything she did, but just how I feel about myself.
I think you should into therapy. It sounds like this issues are pretty debilitating to you, and I think you deserve to be happy. I think being able to talk to someone openly about how you are feeling will make it less overwhelming. I've been to therapy in the past and it helped. I think if you worked on how you feel about yourself you will find it easier to connect with people. I think you are worth something and I hope you get help.