Why are my "friends" assholes?

I've been going through a phase of my life where I feel an emptiness after losing a long term relationship and have nothing to do but school and work and I want to get out and have fun with my friends but they're always assholes to me. Some don't answer when I text to hang out, and two of them always cancel on me like an hour before we're supposed to do something that night even when they're the ones that arranged the hang out! (which is a rare as hell occasion for these people) I've been stood up about 3 times in the past 3 weeks, mostly with the oldest excuse ever, "I'm sick". Like today, one of them said she was sick, then said she could go and she would text me, and never did. I have only one friend that always answers and asks to hang out. One of my friends says she has to "hang out with her mom"...we are all 20 years old and up. Why do they suck? We all have fun when we do actually get to hang out, is it like a disorder or something, wtf?