Love triangle, what should I do?

OK. So. A friend and I love each other, in “that” way. She says she’s loved me for over a year now, but we’ve just recently (secretly) gotten together. However, she has had a boyfriend for almost three years, that she says she doesn’t really love, but she feels she can’t break up with him. Am I in a position to demand anything? I feel like a homewrecker as it is. And he wants to MARRY her, he’s kind of planning on it. This is no tweeny situation.

Also: I’m a girl, not usually a lesbian though . . . and she’s my roommate.