Sigh. I do not envy your position. *hug* I am sorry you are hurting.
Its hard, there are no rights and wrongs in how do deal with it. There is no guide book that says - if this happens, do this.
You make your own guide book for how to be in right relationship to each other that says to do this or that.
We have our playbook.
It is meant as a tool in times of having to discern, solve things, or call into account.
Say it were me and my DH.
I find out he's had 7 people and not told me? I check playbook. 7 strikes for lying. He's out.
Say it were my DH trying to determine his best behavior as the things unfolded in slow motion:
"I want to hit on her friend/coworkers that she's having a project with without telling her. Can I do that? Check playbook."
No. Would not be giving her clear communication not to tell her.
No, would not be helping to tend partner's buckets and providing emotional safety.
Ergo -- do not proceed without checking in first. So I should ask her for the ok.
"I messed up and got all sexy with her friend. What do I do? Check playbook"
Lies or lies of omission are a one strike. I don't want that. Better to hard truth it and apologize and ask to work it out on 3 strikes.
"Do I have 6 more affairs? Check playbook."
Hell no, I already have to make good on the first one!
I want to be able to work through it, but I don't want him to abuse that.
You cannot control his behavior. Only he can.
Are you even willing to trust him again? You don't sound like you are.
And I feel like I dont know. I know he will never do "THAT" again. But that doesn't stop him from doing other things that aren't "THAT", but just as difficult to deal with. He is a man that does not put a toe in to check the water.... he jumps.
Then you have answered yourself. You cannot feel emotionally safe with him. He will not carry your buckets of mental health, emotional health, physical health, or spiritual health with minimal slosh. He jumps!
If you not not willing to be sloshed up, end it. I know I wouldn't be willing for more of this.
Polyamory and polygamous relationship can be done well -- but not like this. He's got weak interpersonal/honesty skills and he's got "kid in the candy store" probs.
Knowing what you know about him -- why would you want to sign up for more? What's the return on continued investment here? Is it worth while for you?
Only you can answer that kind of thing while you are in your 6 mos of soul searching. Be careful and take care of yourself as you heal.