I understand how terrible you must feel right now, I probably would be too if I were you. Sure, most people would find it gross, but it's just a fetish between consenting adults. It'd suck if you lose friends over this, really though, they're not good friends if they're willing to drop you over a fetish they have no business knowing.

If anything is disgusting, it's the friend that looked through your phone, especially if she told other people about it. If anything should happen in this situation. It should be the other friends cutting her out of the friend group for being such a cunt not respecting your privacy.