I feel your pain, Sadness2011. I am also going through seeing my former best friends from high school reunite. Mostly it's on Facebook (I loathe that site now :/) and they don't talk to me at all despite my replies on their posts. It's real pain for us and I am just happy you went to the party. Were there others that you knew or felt comfortable around? Sometimes other people can be a distraction from thinking about the past and the fact that your friends and former boyfriend aren't with you. For me, running especially helps. It "exercises" your thoughts and you end up more physically tired and mentally tired. Another thing that might help moving forward from those people, which is what I think you should do in this situation, is focusing on a hobby after work or school or try to do something like a ritual everyday (Sudoku, cooking a new recipe, cleaning a part of your house, going on a long walk, practicing yoga, ...).

So if you've tried things to reconnect, don't linger in this sadness anymore. Drift off into a new world where you can be healthy and happy. I might have those medicines checked out again if I were you, especially if you have been on it over five months.