My guess is your MC isn't trained in how to heal this sort of damage.

1. Your H may bring up other problems with the marriage, but what he's DOING is rationalizing his AVOIDING the fresh wound of the affair you had... He's not dealing with the other things constructively, he's just grasping for excuses to ESCAPE the pain... MC is PAIN.. It means taking the bandages off, poking at the wound, exposing it to the air and the light ... Its a LOT more comforting to cover it up and HIDE the would and never look at it... That's what he's doing..

Ignore the "we weren't meant to be together"... "it won't work", and "im done".. it's classic wayward script..he's trying to talk HIMSELF into detachment, he's not even talking to you, he's just yammering to his own subconscious and possibly some guilt... He knows' he's trashing a marriage right now... I suspect your improved behaviour has caught him off guard and is tugging at him...

I am a bit confused.. you are both seeing the same therapist but the only subject is parenting?

How much research and experience has this therapist had in healing infidelity?

If you like psychology and do graduate level work you would benefit from

Sue Johnson's Hold me Tight. The whole book is dedicated to discussing how to heal emotional wounds ... she addresses them like a surgeon... Brilliant stuff... not the best writer, but its well worth a read...

If your H criticizes trivial stuff when he shows up in your home he is likley just showing the hurt is still there from you cheating.

1. His criticism is just his own hurt lashing out at you - he hasn't processed
2. He gets reminded of his hurt when he's close to you... Which means he likely has some warmer feelings for you still too... And he fights them off with the outbursts... I think he's likley wrestling with a LOT of emotions he is NOT equipped to handle right now... and he has an idiot brother and a OW who aren't helping him either...

Don't take his complaints or his negativity to heart, its classic stuff we all hear... My wife had an affair off and on for over two years... I heard "I am done" and "I'm leaving" and "I hate you" etc more times than I can count...

OM's gone now for six months and counting... I get only warmth from her now.. she's past he withdrawal I think too... You just have to focus on the positive stuff and keep that fueling you until you get over the hill and things are easier.

You need to get some scripted answers for him when he next shows up.

Pursuit isn't a good idea no
But you just acting as if you are OK with him cheating on you and pushing for divorce isn't helping your case.

I think you need a good script saying that you want to be the best mother you can, and that means doing everything you can to recommit to your son's husband...

And you go to FT on your own... a GOOD one. NOT one that tells you to move on... lose that clown.

YOU decide when you are moving on.. NOT the FT... good grief.

I think you setting an example of a committed parent and spouse will help, he needs to know you want to reconcile WITHOUT you pressuring him to do the same... lead by example rather than by lecture...

He does need to know you are willing to explore reconcilliation... And that he's hurting his son right now... that should be in the script...