Sorry you are in this sutuation You have to face this Ladyfey seems to me IMHE, you have 2 choices here, one you 'tell' ( not ask) him to cut communication and prove himself to you or two you ask him to leave while you decide if you are going to continue this relationship. He appears to be calling all the shots here and you do not have to tolerate this situation. In many ways you hold the cards as you know about her now
( I wish I'd known then what I know now as I may have retained some dignity after my ex and I split) I only found out after we'd decided to a temporary separation that he was carrying on with a client.
You need to take control , I know it's tough with kids but you do deserve better as he is having his cake at the moment , think what he's telling her about you as that may help you get angrier. ((Hugs))
Ive just found out my husband is cheating, I know we were going through a bad patch (nothing major not talking fighting over silly things trying to work arounf family life and work) but to cheat it has flatten me for six I dont know what to do on one hand I want him to stay but every time his phone beeps or he disappears he is on the phone with her they work together which doesnt help so the next business trip he will be with her how can I have him stay and ask him to not see her when they have to work together what to do, where to start I havent a clue with have small children together and we are financially dependant on him Im well and truly lost