I am glad you are going to counseling.
You have a lot broken in that marriage.
YOU are not sounding like you want a polyship. That is your right.
Yet YOU are the one asking the practical "Is this the time to open? How would it be"?" questions though. Not him. That tells me that he's sooooo not prepared to do ethical polyamory.
That sure ain't it.
So... Proceed with caution and see what you glean in counseling. Has this been an emotional affair? I dunno is this article helps you to take to counseling.
I am sorry you are going through this. I hope he straightens up his act.
This is SO inappropriate in all sorts of ways and esp this.
He wants to stay friends with her sand I told him I can't demand a stop to it. He doesn't want me to contact her and say anything as apperantly despite her offering threesomes and stuff she doesn't know anything and it is all his doing. Not quite decided how I feel about that. Feels like he is protecting her and wants to wrap it all up and away. Still think about contacting her or asking to read their messaging history to get an insight into what actually happened but not decided whether this is a good thing or not either.
Maybe counselling will help with that too...
He TELLS you that she's offering threesomes? WTF?
I told him I can't demand a stop to it.
Oh, yeah you CAN! You can have that as a reasonable SOFT LIMIT.
"No talking to her til our counseling appointment so we have a counselor's help in setting reasonable boundaries that are healthy for the marriage while we try to rebuild trust/connection here! We are in a time out!"
How is that unreasonable!? Sheesh. He's being so fresh.
Again I am sorry.