I totally can relate with you. I have always been the "center" friend, I was friends with everyone always torn in between when one of them didn't like the other, always there at midnight if they needed a ride home from the bar, always babysitting their kids, etc.
I lost a guy best friend in March this year. Most heart wrenching thing ever. I didn't grieve the way I needed .. I became angry .. emotional .. snapping off when I didn't even realize it. Frustrated almost that NO ONE else could HELP ME feel better (not that it was their place I guess) .. but all within a week I lost a handful of my close friends (10+ years friends) they all jumped on the bandwagon everyone quit talking to me. Put me in a deep depression I felt I had NO ONE. 6 months later not 1 of them still has tried to see if I'm alive or dead. It hurts and I can't let go. It consumes me at times. All I want to do is forgive and forget and "get over it" but it's not that easy .. I feel your pain...only thing I try to find positive is to know these people are no longer a part of my life .. I don't have to "do" for them anymore .. they weren't a friend to begin with I guess. (Hard to imagine) I pray for the day I can break free and let it all go and it not bog me down.
Good luck...I'm here!