Thanks all. He didn't come home tonight because he said with no trust there is no relationship. He sees the issue is that I don't trust him and should have known that he would never use a dating site (despite the evidence). He alternately says that all of this is because I don't give him enough BJs. It is so painful and surreal - all of this seems crazy. But again, thanks for your advice and kind words. I do have a couple of family members around and a pretty good support system. I will be ok - I remind myself I need to be for our kids.
-OP
I would respond, perhaps by email, that he's entirely right: without trust, there is no relationship. By frequenting a dating site, he has violated your trust. By blaming you for his visiting a dating site, he is violating your trust that he would address issues in the marriage directly. And now for you to be able to trust him, you need to know the extent of his activities: has he been dating, is he seeing someone, has he had sex with someone, does he want out of the marriage? ITs unlikely, however, he is going to give you concrete answers and unfortunately his actions--gaslighting--suggest he's guilty and trying like hell to blame you. I'd probably start with cellphone and credit card records and see if something comes up. Has he had suspicious behavior? (eg working late, traveling, etc?). Has his refusal to have sex been recent or sudden? has he addressed that with you directly? It sounds as if intensive counseling is necessary.