<human>: Can you condense the text into three sentences or less?

The other night after getting back to my friends apartment after NYE celebrations in downtown Minneapolis, I was hanging out in the lobby with my friend and a few other random people and sparked up a conversation with another guy. After bs-ing for about 15 min and being cool with one another, the conversation turned sour somehow and we started arguing about the most inane topic (watches) thanks to the alcohol. Well, he must have gotten offended by it and started getting more confrontational about a subject and was very much in my face so I said to my friend lets go up to the apartment. He continued to get in my face and I told him to back off and when the elevator door opened he punched me in the face and I went down, landing on my cell phone in my pocket shattering the screen. He then proceeded to punch me repeatedly in the jaw and the sides of my head and on my back and neck. I never touched him once. He got out on the next floor and my friend and I went in the apartment and cleaned up and went to bed. (There was a good amount of blood). Yesterday morning I wake up to bruises on my forehead, a busted lip and a swollen jaw. The guy must not have remembered that while our initial friendly conversation, he gave me his business card which I am looking at right now. So now I am curious as to how I should proceed with this? Should I let it go? Should I contact him? Should I file a police report?
<bot>: Drunk conversation ended with stranger beating my ass and forgot he gave my his business card with all his information before doing so. Need advice on how to proceed.