Don’t want to/can’t go to wedding

Hi, I suffer massively from social anxiety and I’ve been invited to go to a friends wedding. It’s this week and I really don’t think I can do it. I have this year started suffering from panic attacks as well to top it off.
I’ve been meaning to tell him I don’t think I can do it but I just get anxious when it comes to it. Do I say I can’t go now? (My thinking is he’ll hate me because I’ve told him just before the wedding, like having negative news before something good/special).

In my head I’m contemplating of not going and I know that’s a dick move….. I feel like/ know whatever choice I make I’m being bad friend.
Any advice is much appreciated.