Wow, you've got alot on your mind right now. I'm sorry that it's such a rough time for you.
The fact that Erica is bound to bring back some feelings in you that you thought that you had put to "bed." But they are going to spring back every now and then ~ you can't stop people from dying ~ that's a part of life, and it's going to keep happening, unfortunately.

You and your therapist will have to come up with better coping strategies ~ something isn't working.
Then not doing as well on your grades as you thought was a "downer." When you're stressed, it's hard to concentrate ~ and you were certainly stressed.
Girls can be so hateful sometimes. They invite a bunch of girls and then leave one out. That is painful ~ but why not have your own get-to-gether?? Ask some girlfriends to YOUR house or to go to the movie with YOU?

Get a bunch together and you and your friends can have a great time together, and perhaps have a coke/pepsi afterwards. It could be a lot of fun!
I wish you the very best hon. God bless. Hugs, Lee