Sex question

I’m 25 now and I’ve been with my boyfriend for 4 years and we have two kids together. He wants to watch me have sex with another man.. it’s his thing.. he’s into the whole threesomes and whatnot.

Mind you, my boyfriend is the only man I’ve ever been with and I don’t feel comfortable having sex with another man, let alone have him sit there and watch me.. he wants me to experience someone other than him. But I don’t care to. I don’t want to experiment with anyone else. Like I’m all in for trying new things, like different sex toys, whips, role playing.. stuff like that. But I don’t want to have sex with another guy. And he refuses to understand me.

He wanted to have sex with another woman and have me record it. I did that only because honestly, our relationship is shitty and I don’t really care that he did it. And to be honest again, he looked stupid doing it lol he couldn’t stay hard. So it was amusing. He made me dress up so he could look at me and do her lol

Afterwards we had some really good sex lol so that was fun. He thought it was going to upset me. But honestly after everything he’s put me through, I don’t care.

But sex means more to me. It’s not just something I do with anyone. I do it with someone I want to be with/care for. Someone I know!

What should I do??