>>33778052 (OP)
it is YOUR gf, you know her better. will she?
but seriously, every thread like this have only one right answer:
admit it. if she will just immedeately brak up with you - she wasn't your person and you meant nothing to her, get over it.
if she doesn't - no matter what she will think, it will lead to the development of your relationship. maybe you will even come up with a way to make your fanatasy real. even if she will be absolutely disgusted she will deal with it because she loves you