No, it doesn't sound "reasonable". She goes out the door, she's responsible for herself. See, when people are engaged in an affair they have this fairytale view of the world. Her bubble's about to burst, big time. This is why I have always said to contact a legal representative. Marriage is about love. Separation/Divorce is about money. You need to find out what your pain level is with relation to the money side. Personally, I wouldn't give an lying cheating spouse a dime more than they were legally allowed, but that's my very own personal view. After all, what will your next relationship say if you're still funding your current one at a level about what is necessary by law? It may sound compassionate, but it's not a mercy to hang a man slowly as they say.
I guess I'm feeling a bit hard on this kind of person lately. I do hope things work out well for you personally and your kids.