confession about my relationship and class

hey everyone i need to confess something that has been eating me up lately. im a high school teacher in my late twenties and ive been with my partner for almost 5 years now. we are both very passionate people and one night after a long day of work he mentioned how turned on he gets when hes thinking about the kids in class, specifically one younger girl who reminds him of me sometimes. at first i was shocked but then as we talked more i found myself getting curious too. we agreed to try something out once, just for fun, where i pretended to be a student and he pretended to teach me some kind of lesson. it felt weird but also kinda hot, like this taboo thing that shouldnt exist between us. now im scared maybe i crossed a line somewhere? do you think its wrong if no one else ever finds out?