If your ex flipped out that fast and called you a bitch, then would you really want to gack to him. The new guy came at the right time and your ex didn't answer his phone at the right time. I think you you did the right thing by hanging with the new guy. What did your gut tell you?
If your ex can't understand "shit happens" and to grow up, then I'd just say ignore the douche. You weren't in the wrong, in my opinion for what you did. And besides with crap like that, "Just brush that dirt off your shoulder." don't let that kind of crap get to ya.
its good to hear i was in the right 