You said it yourself, "I am only 20." You've been through a great deal of drama - drama that relates to the romantic notion of being swept off your feet, being the "beautiful couple," having intense entrances and exits. This is the stuff of which Danielle Steele novels are made.
Unfortunately, you are not a character in a novel. You are a real, live human being. I would suggest you think about some of the comments you made regarding this man: "drunken driving," "embarrassing fits in public," "starting a fight with one of my friends." You may have shared some beautiful moments with this man, but beautiful moments are not what makes a relationship solid.
You've been through an emotional meat grinder, and you are far too young to be scarred for life by this mess. I'd suggest you get into counseling and find Al-Anon meetings in your area. You CAN heal and you can pick up the broken pieces of your life - with time, patience and a good dose of self-love.
Be glad you didn't end up marrying this man. He sounds toxic. I hope he finds recovery. If he recovers, works a solid program, and wants to resume a relationship with you IN TIME (I'd say give it a minimum of one year), then there is hope.
In the meantime, you have a future ahead of you. Please don't let this relationship trash your hopes and dreams. You need to find out what is at the bottom of all the rage and grief. This relationship certainly contributed to those feelings, but perhaps those feelings were there, in part, before you ever met this man.
Please keep posting and please seek help. You deserve it.