If you respond I would do it in a joking way without giving any information. Say something like "I am a married woman, why would I be dating...LOL -- Oh that's right it is you that is married and dating. Too funny" In that way it puts it back on his actions.
In this way you are responding -- just not in the way your H wants and maybe it will diffuse his anger. You know when they are in the fog babble that they rewrite everything. This is just another way for H to prove he is right having his A. You do not need to buy into that. good luck
Me 53 H 50 D16, D29 M 22 years bomb 7/08 INH - alien pod replaces H 8/08 - OW (direct report), I work there also bomb II - H moves 10/1 expose ow 10/22 D to be final 9-09