One, do not take $hit for one second about your decisions about the safety of your children in/re Covid. He may act like an a-hole about this trip and quarantining, but don't let that wear you down. I'm just going to give you all the reinforcement I can here. This virus is a big, big deal. Children are getting it. Even if they aren't too badly affected now, we have no idea how it could affect them in the future. The heart damage they're seeing to young and healthy athletes is very freaky. if your H wants to go off and see the OW (sorry, I'm also having a hard time understanding what work trips are remotely necessary right now), he can go ahead and quarantine for 14 days when he gets back. Do you have any quarantine rules in your state/county/city? That can be a pretty simple thing to follow.
Two, I know you know this, but do not let yourself get dragged into his ridiculous narrative. Reading your diaries from when you were a teenager? And then trying to tell you that because of what he read in your TEENAGE DIARY he can criticize your feelings for him, your husband and the father of your children, and what you had said to him about how much you loved him? What an @ss! Seriously! I hope you let that garbage just go in one ear and out the other.
I also had read something you'd posted that had stuck out to me awhile back, not sure if it was on this thread or your MLC one-- about how H had let you down in a co-parenting moment with your kids. Is there a way you can arrange things so that you don't need to depend on him for this kind of thing? that is one little thing I've been doing-- in the moments where the old me would have called on H to help with something, from getting down a dish from a tall shelf to talking to a recalcitrant child-- I am taking a deep breath and diving in on my own and just getting it done. it feels good. You are such an incredible mom and organizer I have no doubt you can handle everything on your own with your eyes closed if you needed to... and maybe it wouldn't be a bad thing just to imagine he is totally unreliable for the moment (even though he does have moments of reliability) and just take care of $hit on your own like the bad boss mama you are.
How is the joint business going in all of this?
Me (46) H (42) M:14 T:18, D9 & D11 4/19 - 12/19: series of escalating BDs 9/20 - present: R and piecing