I think you'll find a lot of girls wear make up. NOT to lure guys. But to make them self feel pretty. You talk like she has done wrong by you, by wearing makeup. I understand that you found her unnatractive with out make up and that's fine, but I don't like how you were saying you felt cheated. She can't have been that ugly without make up, It doesn't work complete wonders.
If you don't find her attractive fine that's your problem don't go blaming her saying she shouldn't have worn make up. If she hadn't of worn make up then you wouldn't have noticed her and you would not have know this great girl the past 7 years. Make up or no make up she can't help how she looks.