Absolutely he should be the one to go. I think you're at the point now, though, where staying or going isn't about principles or winning. It's taking back the respect and dignity and CHOICE that he has stolen from you. Is your emotional welfare less important that the principle of who should leave? I imagine you're feeling a lot of disgust and anxiety right now - you might find the book 'Cheating in a Nutshell' illuminating.
You don't have to do anything as a team if you aren't a team any more. I did struggle with this at first when I started my divorce process. Eventually, it did become a symbolic point of pride for me to do it. I saw it as extricating myself from an unacceptable situation, regardless of the fact that my X created it. It was empowering. The marriage is a business deal gone wrong, and if you are ready to extricate yourself, treat it as such.
You don't need to argue how much the house is worth. You pay for a private valuation or you ask your broker to revalue as part of a potential mortgage refinance to buy him out. This doesn't necessarily mean you are moving forward with S/D. Your H doesn't need to agree to it either. You are free to gather your own information. He's arguing because he feels he's losing control. You are so strong, May, and you have options. You can do this!
