I had some trouble with something like this after I broke up with my abusive boyfriend. I even ended up getting sick to my stomach any time my family went to visit anyone, or to church, or anything where people normally get into conversations. I remember spending almost the whole evening in the bathroom at one family friends house with diarrea and nausea SIMPLY because we were at their house. Within minutes or maybe an hour of leaving, I was fine. What helped me is just forcing myself to go to the situations that upset me like that. Mostly starting with smaller groups that didn't upset me as much. Eventually I got over the fear. My situation was triggered by something that had recently happened so may not relate as much to yours. I do understand the overwhelming feelings and the lack of ability to really reason them away. My Grandma was a good advisor and confidant during that time. Find yourself a friend who can give you the moral support that you need.
WebMD
Tips To Help You Get Started
* Identify sources of stress: Try keeping a journal and note stressful as well as positive events.
* Restructure priorities: Emphasize positive, effective behavior.
* Make time for recreational and pleasurable activities.
* Communicate: Explain and assert your needs to someone you trust; write in a journal to express your feelings.
* Try to focus on positive outcomes and finding methods for reducing and managing stress.