Should I wait because otherwise I might lose her, or go for it because otherwise I might lose her?

Alright, so I’m in this play. I feel more strongly about one of the actresses than I ever have about anyone in my life. We’re currently good friends, and she’s often affectionate, but I honestly can’t tell how she feels about me romantically. The play is a Greek Tragedy, and the aforementioned woman is playing my sister. Predictably, our characters have a weird, borderline incestuous relationship.

I fear that if I tell her about my feelings, the nature of our in-character relationship will lead her to say no.

Our play will show just before Spring Break, which means that if I wait to tell her until after the play that gives us a little under two months before Summer, provided she feels the same way. The woman in question is also graduating at the end of the Spring semester and will be going to Med School. So, I also fear that if I wait, we’d break up within a very short time.

Any advice, or even a pitying pat on the head, would be much appreciated.