The other night I (26 f) found out that my partner (30 m) had sex with someone a few months ago when we first became open. I had been under the impression that neither of us had done anything physical with anyone. I had an incredibly emotional reaction and felt so hurt. My mind immediately went to all these questions and wanting to know everything. I'm still feeling so sad about it, and almost feel like I'm grieving. I also feel hypocritical for having such a bad reaction to something I wanted in the first place. I'm wondering if being open is something I'm still comfortable with.

Did anyone else feel really sad when you first found out about your partner sleeping with someone else?