"Beards"

When I came out to my friend, she told me that she still supported me and loved me. She said she had a crush on me, and now understands why I never reciprocated (she was making it blatantly obvious). One thing she said, though, was that she has no intention of being my "beard", and I can get that idea out of my head. I laughed and said that I never intended on having a "beard".

It's been about three months, and our "relationship" has accidentally gone public: Everyone thinks we are dating. Even though we both have told everyone that we are just friends and we talk boys out in public (well, she talks boys, and I listen), no one is getting the hint that we are not dating.

A few days ago, a friend of mine was walking by when her and I were out and said "way to go, bro!". I looked at her and said sorry. She shook her head and told me, "It's fine. I've kinda gotten used to being your beard." I feel terrible that she has been roped into being my straight-disguise. Now that I am ready to come out though, she told me to wait after prom. That way she can claim she didn't know and we'd "go back to being just friends". I don't know if she was joking or being serious.

I guess my question is: how do I deal with this situation? Do I let her continue being my beard until after prom? Or do I come out now to stop putting her through that? (I know she said she has "gotten used to" it, but I can tell she would much rather not be).