I broke things off with my FP because he was in an open relationship and I could not handle it. I was the secondary partner and would compare myself to his girlfriend and other girls he dated all the time. It drove me insane. It was "don't ask, don't tell" which ramped up my distrust and paranoia. One time he sent me a photo taken on one of his dates (as I found out later). The girl was gorgeous and that caused me to feel insecure and split on him. His primary gf would also post couple photos+lovey comments on social media and seeing them made me want to die. 

Even though I was in so much pain back then, I still to this day doubt my choice to end things. To me he was THE perfect man and everything I wanted. Maybe I could've just stuck it out, worked on my insecurities, even tried to be friends? We've been no contact for months now and I'm still spiralling. Feels like I'll never like anyone as much as I liked him. Anyone with experience with polyamory/open relationships who can relate or give me some advice?