I'm going to cancel plans with my bestfriend
Why are you canceling plans with your friend?
Because of his bad history of showing up
You shouldn't make plans with someone, even if they're unreliable, if you don't intend to follow through.
I don't care. If he's going to do this every time, then forget it.
Your frustration is understandable, but you need to show up -- and tell him how his behavior has affected you, and many others, most likely.