In my situation I wished I would have said “you want a divorce? Do you need help packaging your bags? Then when out and started my new awesome life. It’s really that simple and it gives you the best chance of your spouse changing their mind.
Right now you’re in a tough spot because if you give him six months to try out his new girl it will psychologically beat you down for another six months. Then if it doesn’t work out you get your husband back only because his affair fizzled out. Is that what you want? Or you make it clear that you don’t want a divorce but you refuse to live in limbo for another z6 months. You go out and live your best life. If he wants to join you later on then it’s something you will have to discuss then.