I can relate to this. It is an awful place to be in. loneliness, in my analysis, is a symptom of a deeper issue, like shyness or social anxiety or depression.

I understand that when you feel lonely, it is difficult to take in any advice, and become very defensive and probably depressed, but once your perception widens in times, make some effort to overcome the problem. Try to accept yourself more. Enjoy your time alone. May be then, as I hope in my case, others would find me interesting to talk to, and break the shell I've lived in for years. If not, then you are enjoying your time, at least. I learned that I don't really have a choice but to learn to live by myself until something beautiful happens.

May be I am the last one who can give you an advice in this, but loneliness with me is a very long and painful story.

Hope you will get better soon.