There are so many things in life worthy of stressing over, finding out somebody is gay/straight/bi/a little green man from outerspace just ain't one of them.
Back in undergrad, 2 guys on my floor lived together. They had been friends forever. One of them was gay. The other guy told me, "Yep, Bill just told me one day that he was gay. He had been my friend my whole life....what do you do?"
They got along great, and from what I remember, Bill didn't have any problems with anybody on the floor. He was a good guy who just happened to like dick