My husband had an affair a very long time ago, so I do understand at least some of what you are feeling and going through now Spdbody.
However, what I don't understand is why you are still with him as you obviously 'dislike' him, and you don't sound as if you even want to be able to forgive him? This situation is definitely not what is best for your children. Even if you think they are not aware of the toxic atmosphere, they almost certainly, absolutely, are.
Unfortunately, there are various scenarios for how you, your husband, and your dear children, are going to fare with your present attitude, and sadly none of them is good. One of the most likely repercussions is that your husband will leave you sooner or later, either facilitated for him by him having another affair - many men don't seem capable of just leaving if they are not happy, they prefer to already have another woman waiting in the wings - or he will just leave anyway, maybe to live with his DM for a while if that choice is available.
Do you really want to be in the position of having your future forced upon you and your dear children, because you actually made it impossible for him to keep living with you? Being/feeling such a dislike for someone you presumably once loved, and treating them in such a horrible way, is not only bad for him (I know you feel justified in continuing to punish him), and awful for the children, it isn't actually doing your own self-respect, and even self-like, any favours at all.
Please believe me when I say that you do not want to become a bitter and resentful person - that would be so bad for both you and your dear children. For whatever reasons you want to stay married/living with him, I think that you desperately need to seek professional guidance both for yourself, on your own, and with a relationship counsellor for the two of you together. I cannot see how your relationship can possibly succeed long term without any indepth counselling.
I really do understand that you are still hurting, and want your husband to suffer, but again, sadly, in fact very sadly, that is not what is best for either you or your DC. 🩷 xxx