I'm going to avoid my friend
Why are you avoiding your friend?
He was interested in my girlfriend
Instead of avoiding him, you should confront him directly. Speaking openly about the issues between the two of you will foster trust and respect. It will also allow you to solve issues before they get any worse.
You're a loser for not realizing that my friend is the enemy. Avoiding a person in real life is a good tactic.
Is it possible that it didn't go down the way you thought it did? You should talk with your friend before doing anything rash.