My Roommate Has Feelings For Me: How Do I Shut It Down?

I've been living with three other roommates for a little over a month now. One of them is my sister, another is her best friend, and the last is a guy. They all went to class together and are 8 years older than me.

About a week ago, my guy roommate expressed that he had feelings for me and I immediately shut him down (for a number of reasons). I had just left for vacation and I told him that I didn't want it to be awkward when I got home, then he promised that he'd never make a move on me and that everything would be normal.

I knew that was going to go down the drain as soon as he got drunk, and I was right. He texted me while he was out and made some comments that made me a little uncomfortable since I don't return his feelings at all, and I know he has at least one restraining order on him, if not two, from girls he was after or had dated. (If I had known any of this prior to moving in, I wouldn't have been okay with living with him). I was curt and to the point, but I doubt he'll remember it when he gets drunk again.

I know I have to shut him down harder if I really want him to leave it alone. BUT I'm living with him for the rest of the year, so I can't do anything that will really make this whole situation worse. If all else fails, I can get him kicked out but I'd like to hold off on that as long as possible. How should I go about it? How can I REALLY shut him down so he stops making advances?