The only time I came remotely close to this sort of thing was when I met a 15-year old girl at a community theater while I was a teacher (not from MY school, btw). At that time she was just a casual acquaintance, and we didn't even really talk that much.
About 5 years later we had roles opposite each other as "love interests." We had a little minor fun off-stage, but that was primarily for the purpose of getting through on-stage weirdness. If that had been going on 5 years earlier, I'd likely be sitting in jail right now.
Don't do it, man. Just don't. Find one of her friends about the same age, give it 3 or 4 years, and see what happens. You'll get to be with a younger chick, it'll be legal, and you can shame the crush you have now. Assuming it works out, of course, and you don't meet someone your own age in the meantime.
Something that I've found works for me is that I also get along with much older women. I've never been a "boy toy," but it isn't like I haven't tried! It's just too hard to find the right woman for that, and I'm settled in a good relationship at the moment. It would certainly be much safer than what you're trying to do now. Get out of there.