My bestfriend has sex with MY boyfriend

Yes they had sex together, and honestly I don't know how I feel about it.. we had a very awkward 3 some few months ago and now today my boyfriend asked if we wanted to do it again.. and I didn't really want to because my heart shattered when we had the 3 some and watch him have sex with her.. I couldn't handle it... I told him I didn't want to today and it ended up with him and her.. all I could say when he asked if it was okay was "idk" but they did it anyways... she didn't even come to me and ask if it was okay.. she just went for it and haven't said really anything else to me about it.. my heart just hurts... knowing I sent him a message before they started and knowing why he didn't answer was because they were yeah you know... and I couldn't hold tears back.. it wasn't long sex but like I'm insecure and feel weird... knowing they just willingly had sex. All these things are running through my mind that I can't even list them all.. it hurts, feels weird, all these what if's, and everything you could think of... I'm not really asking for anything but something to get my thought out there... I just want to cry but I can't act like the bad person... 💔