Good for you Green.
Sadly I feel you are in this place right now that I'm hopping you can get yourself out of. Health issues are not easy to take, trust me I know. I've been there, but not with what you are going though now.
Remember this though, life sucks. Yeah words of the wise. Actual what I mean is. I've been there were you feel you don't belong with your friends anymore. The sad part is somethings it's fate telling you it is time for you to move on. Before you take that leap though I have also learned that Friends are there for a reason. We share our problems and help each other though it.
Most of my friends wouldn't be there at the drip of a hat for me like yours are. So keep that in mind when you talk to you friends.
Ask yourself this. ARe they going to feel more hurt that you felt that you couldn't come to them or because you tried to spare them from your pain.
We affect those around us, regarless if they like us or not. As a result we should embrase the fact that they are apart of our lives regarless of the good and the bad.
Take care dude. Remember we are here for you