I'm going to steal my buddy's girl and refuse to speak to him anymore
Why do you want to do that?
Because he stole my girl in the past and I hate him for that.  Besides, she can do better than him.
Taking your friends girlfriend is not something that is moral to do. If he wronged you in the past, talk about it, do not take revenge as it will create a cycle of hate.
I can't wait to see his face when I steal his woman.
What you are about to do is very rude. What your friend did to you is also rude, but doing it back to your friend will not solve the problem. Try talking it out so all feelings are known.