Just tell her, I mean really, does it ultimately matter?
We all die. Life is short.
I'm not trying to sound like a downer (I'm actually very happily drunk right now :P), but it's true. Life is too short to trifle with insignificant things.
Live life fiercely and with much fanfare! Celebrate your love and your capacity for it! Embrace it!
Then again, don't listen to me, I'm a total hermit with no real outside influence - I don't know the first thing about interacting with people, as evidenced by my totally charming naivety regarding this entire situation!