The 7th grade thing is interesting... Some people have a good memory and there might (might!) be a chance that she actually liked you at that point and hoped that you like her too. She could have expected you to admit it to her. Even though you looked gay to her or whatever, that doesn't mean that she disliked you for that. Maybe she was trying to find an excuse to actually talk to you...
Back in high school I had one crazy (but popular) girl after me. She practically molested me on a daily basis (insults, stalking, threatening my best female friend etc.) That went on for three years and everybody knew it. Couldn't get her off my back, literally. By the time we were graduating I thought I couldn't find a girl who hates me more or has worse opinion on me than her. I don't wanna go into too much details but I am happy to be alive today. That's how much (I thought) she hated me. And then suddenly some of my friends confronted her about what she was doing to me all those years and asked her: "Do you love him?" She just blushed. Day after that she started threatening everybody that we were "all going to pay" and we'll see "who's actually flirting with whom". She was totally lost. I graduated. She found out where I went to continue my studies and registered at the same college... But she never had guts to say a word to me anymore, and she looked me much differently.
I was iterating through my memories and I remember that the only time she spoke with me directly (without anybody around) was right after the fight we had in front of everybody. She was totally different and almost cried. Then I went back on to remember how it all started. We had a phys.ed. class playing volleyball or something outdoors. She laid on the grass in front of her friends and started flirting with me saying "come here and lay next to me" seductively. It was all play in front of her friends and I recall smiling sarcastically and going away. That's when three years of mental torture started. I wasn't a hot-shot, far from it. I wasn't even popular but the kinda guy everybody was picking on... But I was above-average in terms of intelligence and education -- elite to a certain point, but with no nerdy-geeky behavior. I should say I was well rounded. Who knows why she liked me so much that she decided to dedicate three years of her life to making my social and personal life miserable. She scared off girls who liked me and I liked. That is the only thing I can't forgive her...
OP, your case is not this extreme, thank God, but there's a possibility that she actually liked you (and maybe still likes you) but is offended by your rejection. Although you didn't formally reject her, she may be using it as an excuse. She may feel insecure or even inferior to you and puts on a mask just as you do. This may all be only a theory, but if I were you I wouldn't leave it like that. I did make that mistake and never openly discussed what happened with her. If you have a chance to talk to her, do so but only two of you.. no masks, no play... And tell her that you liked her back then, but didn't have the guts to say it and go from there.
If you leave it like it is, you'll learn to live that way, just as I did. And it's everything but good for you.
Good luck. Sorry for tl;dr, but I had to share my experience hoping that it may help you or anybody else in similar situation.