This is a very sad story.
From your list of things he has done he does not deserve any love or respect from you.
But I have to say that some women do love the idea of being in love, without much to justify it, and I think this is one of those cases.
The fact he has had sex with a man (maybe more than one) and with a married woman (and maybe more than one) shows he cares not one jot for you or the children.
Apart from his being unfaithful, with so much casual sex on his part (with men and women) there is a real danger of him bringing serious sexual diseases into your house, and I know you dont deserve that.
I would leave him to get on with his stupid fantasy world of casual sex if thats what he wants, it has no place in a stable happy marriage.
I realise your life is in turmoil at the moment, but just concentrate on trying to create a stable home life for your children.
You must also convince yourself you are better than him and dont deserve to be put through all that he is putting you through.