No problem, it's hard not to be vague... I'm not sure how close you were to your roomie (I've been close to most of mine), but I imagine I'd take time to reconsider my friendships, my ambitions, goals, etc. Is your startup really all that important right now, or can it wait a couple of years? What do you want to do now that you're graduating - would you be happier doing something else (academia, traveling, volunteering, teaching)? Should you get a puppy? Or a new haircut? Write an emacs extension? Read that book you've been meaning to (or one you haven't)?
I've been very fortunate not to have lost loved ones so unexpectedly as you just did, but I find letting my mind wander in times of such stress is the best way of coping with loss.
On the other hand, this probably varies by personality, so consulting a professional (shrink, priest, rabbi, etc) is probably your best bet.