First up, your ex is a manbaby coward and a flake.  "I was just high. A lot of times..." Leave that shit in your rearview mirror.  Pretty good chance you will end up being his biggest regret, he absolutely should not be yours. That he cheated with a PoS is his cross to bear, not a reflection if your worth.  Sucks to get hurt, but to me it sounds like you've dodged a bullet. Move on with your life and find an adult worthy of your time and affection.