I would recommend taking some anti-anxiety meds (if you have any) and attending, even if just for a little while. Its hard to handle BP and the phobias and anxiety that goes with it, but its even harder to handle it all alone. It sounds like your friend is really depending on you and I think its important to ask "Has this person been there for me in the past? would this person be there for me if I needed them in the future?" I think that if you do not attend, then you may regret it. Does your friend know what you're going through and how much it frightens you? Even if you only show for a little while and then have to leave, I think your friend would appreciate it and who knows, maybe you'll have a great time too.

I hope you consider going, even if for just a short while. Good luck with whatever choice you make!