Okay - here's my thoughts -
I would NOT get in a big R talk tonight. Why do I say this? He's very confused, waffling, and the least little excuse will send him scuttling back to OW. The OW is probably beleaguring him with R talks right now (wanna bet his sudden homecoming was prompted by a fight with the OW?).If you do the usual - getting upset, issuing ultimatums (not implying this is your usual but the "generic" usual) he will opt out. If you surprise him with 180s (which you've already done by not overreacting to him being out) he may stick around just to figure out who this "new you" is.

BTW - the one thing my H seems to remember me saying to him when he was in his fog was : "you're going to have to work through your issues someday, it might as well be here with me, the mother of your children, who loves you even with your flaws". I would have sworn at the time it made no impression, but that's the thing he really remembers.

So - will you be home before him? Then whip up a yummy dinner (or bring one home), put on some rockin' music that makes you happy, wear some of that sexy lingerie (let that thong peek out a little ) and his favorite perfume (or a sexy new one - Indecence by Givenchy is great, other men compliment me on it all the time). Act AS IF things are going to go well. If you act as if he's going to leave again, he will. If you surprise him by acting as if you expect to have a good evening, you just might. Don't ASSume anything. Sure, he could be coming to tell you it's on again with the OW. OR he could have just had a horrible night with her in which she was clingy and miserable, and if he comes home to a cheery, beautiful upbeat you, he may just remember why he came home in the first place.

Good luck - if you get in a sticky place, try something wacky and unpredictable, okay?

Ellie