I didn't go to my sons wedding.
I am not going to visit family this month after being offered a free ride to their state.

Your friends will understand whether you go or not. But if you want to make sure they don't plan something big, then you not attend, you should tell them. Or better yet, prepare your house, and put something together yourself. A "thanks for being my friend" party.

If you decide you are going. Plan ahead, get yourself something appropriate to wear early, dress up, and fix hair and make up a few times ahead of time, to get used to that presentation. If possible, go to the restaurant yourself alone one day, just to get a feel of the place, and where you would like to sit. I find doing things multiple times helps create the feeling of safety.

Everyone always thinks - oh yes, of course go.... but no one knows how hard it actually is for you.