Thank you for sharing this story, but more importantly, thank you for being a decent human being. I was in a similar situation, but with vastly different results, and I suspect my story’s ending is far from unique.
When my boyfriend pushed for us to become polyamorous, I reluctantly agreed, since it was so important to him. But when I actually acted on our new understanding, he became upset, withdrawing from our relationship and becoming volatile at his best and generally toxic to be around emotionally. Eventually, he wanted me to choose between him and my new partner (whom he had actually found for me), even though we agreed that an ultimatum is the end of a relationship.
My new partner was kind and nurturing and supportive in ways that the first guy never was, and was certainly a much better partner than this new incarnation of him, and it should have been an easy choice, except how could such a thing be easy? But my boyfriend had, in his jealousy and insecurity, told our friends and family that I had cheated on him, and that did indeed make the choice easier. But still, when I made it, he kicked me out, threw away my things, and kept me from seeing our cats, all with no discussion because he’d immediately blocked me on all forms of communication. It was the most hurtful and confusing thing I’ve ever experienced.
As I said, I highly doubt my story is unique. In fact, I suspect it’s likely the ending of most open or poly relationships, because people are rarely as mature as they think they are. But that didn’t make it hurt any less to be vilified and treated so poorly by someone I’d loved and trusted for years. So thank you, thank you, for staying human during a difficult time. I would love to start hearing more stories like yours instead of like mine, and you give me hope that I will.