Most Helpful Girl
I always tell everyone to Let sleeping dogs lie, however, being this is making you 'Sick to my stomach' and it's eating at you like a cancer inside, go ahead and level with her and Then... Realize right then and there where you may stand with her in the future.
You will know then, by coming clean, if she accepts you unconditionally or will Continue in the future to be under her parent's wing over The... Least little thing.
In case there is another chance for romance, if you tell her later, you may have wished you told her earlier because Then... You would be probably barking up the wrong tree.
Good luck. xx