I (30F) ended my open relationship with (52M) which upset him

I (30F) and my boyfriend (52M) have been together for 9 years. This is an obvious age gap relationship. I know to some it’s uncomfortable to some, but we just clicked. I never intended on being with someone so much older than me, it just happened and overall we’ve been so happy together. Plus, my family loves him. Anyway, about 3 years in, I presented trying an open relationship. I was very much willing to not pursue it, I was just interested in exploring other people. He was immediately on board. I will call myself Lucy, and refer to him as Rich.

Rich found a partner shortly thereafter. I found out later that he would tell her, “I’m sorry, you have to leave, Lucy is coming home and she’s not going to want to see you here.” He always used me as an excuse to get her out, even though I wouldn’t be coming home. I would travel about an hour away to stay somewhere since I’m so far from friends/family. I was definitely not going to just drop in. Once he told me this after he finally cut ties, I was angry. I told him it was very unfair to me. If she was “clingy” and romantically interested, he should have cut it off. She thought I was crazy and possessive since he always used my name as a cop-out, and eventually why he couldn’t see her anymore. He didn’t really grasp it, but promised it would never happen again.

He found a 2nd partner about 6 months ago. She’s a very pretty girl, also 30 years old that he works with him at his second job. Let’s call her Jess. We’ve actually always wanted a threesome, and she is also bi, so it was perfect. We had her over one night, and we were all drinking. I got way too tipsy to partake in anything, so I passed out on the couch. Rich and Jess ended up having sex, which was fine by me. I know this circumstance seems to break our rules, but it was a different situation. I was perfectly okay with that. I was stone cold passed out so it didn’t bother me; she doesn’t drive so it’s not like she could have just left, anyway. They had their fun and she took an Uber home in the morning. She woke me up to let me know she was leaving. I walked her out and let her know I’m looking forward to seeing her next time. I talked to Rich later that day and we laughed about me getting too tipsy. He said he would like to have her over again, but this time he hopes I stay awake. Fast forward two weekends, she’s at our home. She ends up taking a bath first, while Rich and I wait on the bed for her to come out. She eventually does, but he did not pay attention to me. They started engaging, and I had about 2 minutes where they were both in a position that I could jump in. After that, I just stood and watched. About 20 minutes later, Rich needed a break. While we were laying next to each other, Jess said she was going to head outside to smoke. Rich pulled Jess on top of him and started kissing her passionately. I was confused. I said, “hun, I think Jess wants to go outside.” But he completely ignored me. After that they started to engage in sex again, and he had her in positions that I could not join in yet again. After seething with anger, I finally decided to go to bed. I felt incredibly pathetic and excluded. The worst part was I had to go back in the room about 10 minutes later, realizing that I has forgotten my phone on my dresser. They were still going at it, with Jess face down. Rich looked up at me and I looked at him with what I can only imagine were daggers. I fell asleep, angry and bitter. His 6am alarm goes off for work and I wake up foggy. Once everything came rushing back to me, I realized that he continued to have sex with Jess one whole hour before coming to bed. He didn’t stop once to check on me, despite seeing how angry I was. I left the house, unsure what to do. Rich called me and asked me to come home to talk. When I did I told him I was furious at him for completely excluding me. At first he apologized, he said he never meant to make me feel that way. I told him he broke my trust and ruined my self esteem. Due to this, I didn’t want us to continue our open relationship. Trust is the biggest foundation, and he managed to ruin it in an 3 hour span. He became defensive, and said it was unfair that I’ve slept with 4 people and he has only slept with 2. I was not keeping count for either of us, it didn’t occur to me. He stated I can’t just start something and then close it at my convenience. He is conventionally handsome, there are most likely women in his life right now that would want to sleep with him, but he said he is oblivious and doesn’t know when someone is interested. I even offered to keep the relationship open just on his side to “even the score,” on the condition he doesn’t see Jess. He declined, stating no other women want him. I told him no deal, then. He called me a hypocrite and said it was unfair. He did say he would stop seeing Jess, but only because it was inconvenient for him to drive her back and forth 45 minutes, and doesn’t want to play taxi. This was 4 weeks ago and I’m just as bitter. Yesterday, he asked what was wrong and I expressed my unhappiness, still. He said he can’t handle this because his auto immune disease flares up when he gets upset, and it can land him in the hospital. He totally disregarded my mental health. A part of me thinks he is right and that I’m being selfish. Any advice would be greatly appreciated.

TL;DR my boyfriend ignored me during a threesome, I want to end our open relationship that I initially suggested because of what happened and he thinks I’m in the wrong

Edit: With all due respect, I’m not seeking advice on the age gap. As stated in my first paragraph, I know it’s not for everyone. Please be respectful of that. Thank you.