Falling for a 'straight' girl

Ok. So to preface the problem I find myself in, I should state a couple of things. I'm a lesbian. But when I moved to a new city 3 years ago, I didn't know how to start over with the coming out process. Back home, I'd been out and involved in the LGBT community. Then I moved here and had no idea where to even start with getting involved and meeting more LGBT people. So I just haven't really come out. Recently I've been more open with the new people that I'm meeting, but I still can't seem to get up the courage to tell my friends that I've known for 2-3 years.

Over the last couple of years I've built up friendships with a group of girls, 2 of which I used to work with and the third is the sister of one of those friends. We hang out a lot and go do things for girl's night but I still am terrified of telling them.

So, the sister? The sister of my friend? She's amazing.

And I really like her.

But she's 'straight.'

She told me one night when we went out that she was kind of bi. And I should have said come out to her right then, but I didn't. I've been crushing on her for quite a while now. If this was just some random girl, I would be much more open to telling her how I felt. But because she is a part of this group of really good friends of mine, I don't know if I can say anything. I don't want to risk things getting weird with any of them if she doesn't feel the same way.

The friends that I am out to know all about this situation and they keep telling me to make a move, but I would really like some objective third party input.

So I guess the question is, do I risk changing the way things are in the slight chance she might be interested in a relationship. Or do I keep it to myself and work towards getting over her and moving on?