It seems like every day he does something nasty. I agreed to let him take the children out as long as they don’t have anything to do with his girlfriend as she is of loose morals (I won’t go into details, but imagine the worst Jeremy Kyle guest you can think of) and they had an affair when we were married. He’s just brought them back from her house! It’s put the children in an awful situation as they felt they should lie to me about where they’d been. One of them slipped up and ended up crying. What can I do?