Ok so im questioning my sexuality and my roommate thinks its wrong?

[Beth]

ok so i am questioning right now and i have told my roommate everything i have been going through, like earlier in the school year i had a minor fling w this other girl and it ended and whatever, but i would tell her every detail about everything. I tell her about anything and everything pertaining to girls and how i feel. So the other day we were talking with this girl from down the hall and this girl has no idea that im questioning, she thinks im completely straight. So we got to talking about gay people and i asked my roommate what she thought and she said thought it was wrong, and i was shocked. I had to play it cool because the other girl was there but she also said that she didn't think bisexuality existed. So my question is, what do i do? do i just let it go or do i stand for my beliefs, because its very hard questioning, i don't know if what i feel is right or wrong so how can i sit back and let someone tell me im wrong? But she is one of my best friends. What do i do?