My roommate is directly responsible for foiling a couple of my suicide and self harm attempts. He has no idea. Just being in the house was enough. When I get super miserable, I have people in the house that I can go to, to game with or watch a movie with. Just to bullshit with. It does matter, it does make a difference. Ya just gotta pick the right person for the right reasons. A good roommate is a good friend, a good support system, that happens to live in the same house as you. They have to be those things first and foremost, or the whole shebang goes.... well, bang.
Having a roommate has helped me maintain my living environment when I get extremely depressed. I don't become a giant pig like I would if I lived alone. Having someone that relies on me for stuff keeps me on some kind of track. I wish you luck and I hope you find a sick ass roommate to have a ton of fun with.