Avoidance? Or a reasonable decision?

Please help. I have been suffering from anxiety for over 4 years now, but I haven`t been in therapy for a 4 or so months because my doctor has been away on a family trip plus I was nearly all good - nearly no symptoms of anxiety/depression whatsoever for months and months.
Until, my exam term this september - I seem to have overdone it (I am, oh the irony, studying to be a psychologist, and I always strive to reach perfection on my exams...). Anyway, got good grades, happy and pleased with my progress, BUT tired - oh so tired from all the obligations I had. Then, suddenly, my attention goes down, I`m no longer able to study, I`m anxious, I`m depressed slightly, in no mood for anything with a slight agoraphobia creeping up on me.
This is all fine, since I figure I overdid it and I probably have burnout to some degree. Then I say, OK I`ll take it slow from now on and try to get back on track via exercising, slowly taking on daily tasks as they come along and see my therapist to sort other issues out.
And then the wedding! No, not my wedding, I was invited to a wedding of a friend which I might add I don`t even really like that much. From day one I create this negative negative picture about this wedding, and days go by, I get ready, dress and all... And then - I decide I don`t want to go in the last possible moment (my migraine on the night before kind of helped me to make this decision plus the burnout plus bad dreams I`ve been having lately which cause me to be oh so tired...). Now if I was a normal person I`d say ok, this is how things are, and I`ll later go to their place and congratulate them and say sorry I couldn`t make it to the wedding. But I am no feeling extremely anxious because of deciding not to go (plus my BF is mad at me because of this, so I also feel guilty because I`m feeling ill???), the build up of anxiety has gone through the roof!
The question is twirling around in my head - did I avoid it because I`m scared of going to a public place with a lot of people there because I`m anxious? Or did I make a sane decision saying to myself that I don`t really like big parties like that, and that, given the circumstances it`s probably best I stayed home?
Any thoughts?
tnx