Been there, done that. Just go to walmart and watch all the people, then understand that you are as good as anybody else with all the rights and priviliges as anybody else.

When you start to feel anxious, take several deep breaths and realize that what you're feeling is your body and not you, so just ignore it. Put your attention on what the person you are talking is saying.
If that doesn't get you there, you might need to get a doctor to give you something for anxiety while you retrain your body with successful interactions with other people.

Also realize that you have the power to leave at anytime, if you really want to. You have only yourself to please, so don't worry about what other people think. Anybody.