Nervous threesome?

So my husband and I were getting it on last night. We were watching porn and stuff together everything was going awesome and he asked me what my fantasy was. I told him a threesome where I hog the girl to myself. He really liked that and said that would be his too. To see me pleasured and him watch.

But he was serious. Like he had me download tinder lol. To look for someone. And wanted to know what our ground rules would be. Like she could only suck him off and kiss his body but nothing in her or she can’t kiss his face. Mostly just for me. And hell yah it turned me on thinking about it. But I’m nervous he would take it too far

Back story, a couple years ago he had an online relationship that went too far and nearly ended our relationship. To me that was cheating. He was emotionally invested in this person and it hurt me. It took a long time to build up the relationship but we are better than we ever have been in the 6 yrs we have been together. But because he is the type that craves the relationship along with the sex idk if this is something he can do. To just have the fun and not have the desire to reach out to her on his own. I’ve also had a baby earlier this year and don’t feel the most confident in my body. My husband raves over me which is sexy but I still don’t feel 100% about myself.

I guess what I’m asking is, if we end up doing it, how do I find a girl. And what are some good ground rules if we do considering what happened before. Because fuck, I’m super turned on and even wet right now thinking about actually doing this

UPDATE

To the girl who loved monsters: what doesn’t sound stable enough. Just curious.