Your not alone. It happens to me more than i wish to admit and like you at the time and afterwards i'm beating myself up about it. But at times when i feel stronger i just say to myself it's my life and i'll take it at myown pace when i want to go out i will. Most people my age are out clubbing all the time and i think i should be there doing it to. But really it would be pretty boring if we were all the same.
Take a deep breathe and don't worry about it people won't mind if you don't go out it's just what your thinking and probably not what their thinking.
So put your feet up and have a nice cup of tea.

Always does the job for me!!