Most Helpful Guy
As hard as it can be and as much as you don't want to, it's time to end the relationship and end all contact.
He is not mature enough for a serious relationship, and could possibly have anger issues along with drug and alcohol dependency issues.
You are too young to be straddled with someone that views you only as a convenience. You take second fiddle to anything he deems better at the moment. He has some growing up to do. I doubt he will change anytime soon. If you stay with him, he will not change. Don't enable the behavior.
He has to want to change. Not just change for a few days to get you back. End the relationship and don't stay in contact with him in any way.
You deserve what you want and need, not just what he wants when he wants it.
Take the time for yourself and your health.
Most Helpful Girl
Move on and never look back. If a guy cannot respect you or care for you, neither should you care about him. Maybe the only reason he ever asked you back was because he missed his punching bag. You, my friend are the punching bag of his.