I recently had a baby and now none of my friends want to hang out with me anymore. 
Congratulations!  That's awful!  DO they not have kids themselves?  Its a pretty typical thing to happen when you're the first to have a baby among them and they don't understand that lifestyle. I've been there.
Well, the father also left, so for me, I've just felt very sad and isolated
I'm so sorry. My sister was in the very same situation as you and I can tell you, she made it through and her daughter is 9 now.  She kept taking a day at a time and working hard and went back to school to become a nurse. You can do it to. Find some true friends who will support you no matter what. 