It is definitely hard, but sometimes you have to push yourself a little to help, even when it hurts. The fact that you want to go and that going in some way helped you is a good reason to push yourself to go again. Eventually, the pain that you feel from being there may stop.

I had the same issue when I first started taking sewing classes. I was deathly afraid, but I really wanted to do it so I went. After a couple of sessions, I got better. I had to force myself to get up and go (early, nonetheless or I'd be afraid of walking in late, too) and I felt wonderful while there and crappy after it was all over.

I think it's a matter of giving yourself small doses of social interaction until you can tolerate that much, and then hopefully increasing those doses of interaction over time. But you have to keep in mind that you're not just getting a negative experience, but a GOOD one as well.