I struggle with horrible anxiety and depression. Mostly my anxiety is higher than anything else.

A "situation" happened between me and a friend of mine, no longer friends, but I didn't consent. But I didn't say no. If I even just see him for a split second I break down in tears and start shaking. This semester I'm going back to school and most likely will see him and he could even be in my class. How do I deal with this? Why do I cry? I should be over it, the situation happened 8 months ago.