Your H needs to be a father to his own kids before having another baby! Sounds like the OW is pursing him.
There are support groups for children going through D. If you're D7 is really having problems with it, try to find one. I know of one in my area that was called Banana Splits. Not sure if it was church-based, or YMCA or what. I know some kids that went and it really helped them. She's at a very tender age...
