I accidentally let it slip I have a foot fetish, and now a girl keeps putting her legs and feet on my lap, and it’s not that I don’t mind, it’s that she does it in public, and whenever she does I tense up.
She’s also had a few other girls put their legs and feet in my lap but she hasn’t told anyone why that I know of. I’m scared someone will connect the dots and find out, what should I do about it?
LemonVibe 
Actually that’s a pretty common thing and nothing to be ashamed of. I hope that part makes you feel better.
As for the girl, she might like you and that’s her way of trying to get closer to you. If you feel that you don’t want to be touched, just say in a kind way, “Please don’t do that. It makes me uncomfortable.” Reasonable people don’t do that. Good friends respect other people’s boundaries. Move away from people who don’t respect your boundaries and stop communicating with them if you feel they cross the line.
Also, if she tells other people, so what? There are worse things and you can just look at people and not say anything. I like to do that to make people feel awkward when they thing they have juicy gossip/racist/sexiest b.s. It makes them look like the jerk they are being at that moment in time. As the old saying goes “better to have people think you are a fool than to open your mouth and remove all doubt.”