Op I would not ever tell him you checked his phone. He will then blame you for checking - in the cheaters mind that’s logical.
Personally I would say someone told you. Refuse to say who. That will drive him wild because if only him and her know he will think it’s her.
You owe him very little now. Honesty is certainly something you do not owe him. It is clear he is happy to lie for months. Protect you and your children. Your mental health is your priority.
I also wouldn’t speak to the OW unless you have speak to her as she will meet the children ( or to ask on his behalf if it’s okay if he can move in with her if he’s refusing to leave your bedroom 😁 ) . She will be a great distraction and if they split there is a chance you’ll have him wailing and crying in your house and telling you about all his mistakes and regrets. And you don’t need that.
She’s gained herself a man who is abusive. Prepared to risk his wife’s mental and sexual health. Prepared to risk his children’s security. Rather than a) talking and saying you need counselling to save or split with Grace. B) going straight to divorce. She’s naive or complicit - maybe both. But if you 100% want rid then let her be his distraction.
He has betrayed himself first, you have to to cheat. He has become (or maybe always was) a liar and a cheat. Two very poor traits which very few people would want in a partner.
He will divorce and not figure out his whys. It is likely that he has poor personality traits that enabled him to do this: low self esteem, requiring ego kibbles (smoke up his arse), external validation, addiction issues, risk taking behaviours, people pleasing, inability to self soothe, instant gratification, poor coping mechanisms, poor communication skills, low integrity, dishonesty, ability to compartmentalise etc. Knight in shining armour complex (KISA). He will still need to figure out his reasons and do the work. If not the new relationship is likely a sticking plaster that makes him feel good - until it doesn’t. Unless he knows why he betrayed himself he will always be a risk to a partner.
Unless he fixes the issues he will remain capable of cheating. Sadly the traits that allow someone to cheat are the traits that mean someone finds it very hard to do The Work involved in creating a new successful marriage or relationship. They want to minimise, omit the full truth, rug sweep and push you to get over it. They play the victim and blame the relationship (or you) for their crappy choices. They experience regret but not remorse.
Cheating is easy, it’s not because a person is sexy or desirable, anyone can cheat. Just download tinder or pop to a sex club.
I choose to remain faithful. It’s a choice that I make. My vows mean something to me. I don’t cheat for me. My husband is really annoying at times, I don’t remain faithful for him. That would put him in control of my behaviour - which is daft. I could even twist that logic and say if he does A I am faithful but if he does C I flirt with my administrator or the man at the bar. So I am not faithful for him, I remain faithful for me. I want my word, my self respect and my integrity to mean something to ME. Because I matter to ME. so I remain faithful for me. What am I if my words are meaningless? My husband is my collateral damage. You sadly were collateral damage to your poor personality trait husband.
I wish you well op. Enjoy your witches party. Spend time thinking about your values. List them and live by them every day. THAT will get you through this. Your values - write them down. And journal around values if you journal.
You are the catch here. Faithful ✅ street smart (this past week has shown that) ✅ focused ✅ putting family, children first ✅ resourceful ✅ and you have been brave posting on here so - vulnerable ✅
Hes a sneaky snake - not partner material.
Good luck op. Life can really suck, but you have an army of us cheering you on and you’ll make new friends on the way, and you’ll be okay. Not every day and not for a while. But you will be okay.