This ugly girl liked me back in high school, now she's gorgeous!?

There was this girl in high school who had a crush on me, and well, I was immature and shallow and thought she was ugly, so I was a to her to boost my ego. Now guess who gets hired at my summer job. I hadn't seen her for over three years, and I was SHOCKED. She is now the most gorgeous brunette I've ever seen, with no exaggeration. I never noticed her beautiful green eyes behind those ugly gles she had, or her perfect smile when she had braces, and she stopped being anorexic thin and now has an amazing body, and wears really nice clothes. Shes also so modest and sweet, not b*tchy like some hot girls. We haven't talked and I don't think she recognizes me yet. The thing is, I'm afraid she'll remember what an *** I was and not even give me a chance. I've matured a lot, honest, and I want to get to know her and apologize for how I acted before. How should I approach her?