Sorry to be black and white, but to me, this is cheating. No, it's not ok. Trust is broken. As broken trust can never be repaired, that would have me reassessing our marriage. I know the same would equal DH pulling the pin as well. Without trust and respect, then love is not enough and the whole thing is a pointless show.

I'm so sorry you're dealing with this. Sounds to me like he needs to grow a pair. You have both made a commitment and choices as to what is best for your family. He's just thrown that in your face. That is both immature and irresponsible. I hope you have IRL support.