Undefeated

I am new here and truly seeking some solid conversation on my situation. My best friend of 20 years recently confessed her true feelings for me, while I am bi, yet engaged to my man. His fantasy of a 3some was spoken of. Entertained, and continued to be pressed by both. She called and wanted to say hello to him, i thought nothing of it. They still have not met btw. I dosed off, when I woke, i heard her moaning and he had his hand on his cock. He jumped up, shoved it in my face, when he saw i got bothered. He passed the phone to me and walked out the bedroom. She asked what happened, and acted confused then hung up. What they dont know is that my phone app recorded the convo. He shared intimate private details about our relationship that were private. She asked questions totally invading privacy. Offering her services of blowing him, since she loves cock and i dont like to do that. And im so prude im not into porn, and watching people have sex live at clubs as they long for. This thought of ever having a 3some is out the window. She ruined my trust as did he. Had i been aware the call was with that purpose, it would have been different. However, I feel they gave into thier lust and threw away a diamond for rocks. Loyalty is hard to come by these days. Would I be wrong to end the relationship? Niether one is owning up, Im getting the silent treatment from both. As if I did something wrong...well I did, I trusted. Thoughts are welcomed PLEASE...Thank you for your time.