How do I stop being mad?

I recently broke up with my boyfriend after he bailed on picking me up after I have surgery. I haven't had the surgery yet, the problem is I'm new in his state and don't know anyone else to ask for a ride. It's been on the calendar for months and it's all arranged with my job to have the time off and my ex decided to start a new job the day of my surgery. Instead of asking to change the day, or asking me if I could change the date of my surgery he just said he can't do it, period. I was shocked. This is on top of finding out he is taking another female on a vacation to Puerto Rico, but he can't even afford to have lunch with me. So I know I did the right thing, even if he is not cheating he still disappointed me on a regular basis. Broken promises, lies, bailing out on me all the time, not respecting my boundaries, all kinds of problems. But how do I stop being so angry? I'm mad at him, I'm mad at myself... I'm just enraged all the time about this.