Over the past 9 ish months, my (20sF) partner (20sM) and I have been talking about opening up our relationship due to health and physical pain issues on my end that prevent us from having sex more than once in a blue moon. Last night, a friend of mine came over and the two of them hooked up. I made it clear that I was okay with this well before it happened so nothing was done in secret. However, I’m currently having a breakdown due to unexpected feelings of frustration at my body, feeling like my living space was disrespected and just kinda grossed out overall. It’s probably important to mention that I have a few mental health conditions that I’m in therapy for which really impact my quality of life. I haven’t been able to eat since yesterday afternoon and have been crying basically nonstop since then. I’m not sure if I regret what happened but I’m scared of what this situation could turn into. I’m afraid that allowing him the occasional hookup with this friend or possibly someone else will make him realize what he’s missing with me and possibly mean the end of our relationship. We did talk about it, which helped a little, but I’m still feeling so disgusted and devastated.