I've just caught up on this and I feel sick for you OP.
I agree with Pagwatch that you are just trying to put a positive spin on things as you can't confront him. This really is so telling and shows just how far he has ground you down. I can't imagine for one second knowing my DH was texting the OW that he adores so much, whilst in the same house, after he's been pouring his heart out to me about how much he cares for her.
Why isn't your anger so great that you went straight in there and told him to leave (you can still be angry and calm!)
How can you be in the same house when you know he's spent months falling in love with someone else and then coming home and looking at you with reducing respect each time?
So whilst you are running around looking after his the children and keeping down the house, he is looking down at you. He was still having sex with you, even though his heart was elsewhere and he was looking at you with pity? Yet you still aren't angry enough to demand that respect back?
Respect seems to be the key here and he's using it like a carrot. He told you he'd lost respect for you as a SAHM but then awarded you a little back when you took his affair so well and kept calm like an understanding wife should. He's controlling you with this and basically treating you like a child (I don't want to say dog) with little rewards for good behaviour. You current reward is that you are still in the running. However a time extension is still required as he hasn't quite made up his mind.
Yes, I've read posts here where couples have come back from an affair but the absolute minimum is for the cheat to at least claim their undying love for their wife. He's not even doing that. Instead, you get another tap on the head for being a good wife and understanding that at least he's being honest with how much he loves the OW.
I know you feel like you've claimed some power back and you've started to tell him your demands for a relationship. However your actions have shown your hand and told him that you were just calling his bluff as he's still there. You gave him a deadline and he didn't do it. Again, he doesn't even respect your boundaries. He's not even pretending you are slightly in the driving seat.
I know it's heartbreaking but surely you can see, when he tells the OW he's might not be able to leave because of the children, that really is what it keeping him. It's not you. Any respect he's let you believe you've earned back isn't genuine. In his eyes, he still has all the power. He's pulling all the strings.
Cut the strings. There have been posters on here who have told of their cheating fathers and how they wished their mother had left. Why do you believe you have to try for the children? You've been trying, for all of your relationship. Your OH hasn't tried. He fell for the OW and then made up a story in his mind about your failings to justify it. Your flaws appeared to him after as you were no longer the object of his lust.
Please please forget his feelings in your decision making. Forget how he's poured his heart out-that's manipulation. He had plenty of time to do that before shagging his assistant! Be strong OP. Be the woman he fell for and then walk away and show him what he's lost. The woman he fell for wouldn't take this crap. He's changed you to keep you down!