Well, it depends on how you think your friend would take it. You say that she doesn't mind people with other sexual orientations, which is good.

But you say she is completely straight? So you just want to tell her to get it off your chest, or actually get a reaction from her? Because both have different endings...

I was in a situation similar to this, but from your friend's point of view, so I can understand to an extent. It all depends on how you think your friend will handle it, really. <3

Sorry that I fail at advice.