Thanks for your quick replies!! I have spent that last month reading through the stickies and posts and have found such a wealth of information and support there - I'm sure I have just scratched the surface.
AH would completely deny his behaviour and on occasion he presents quite well. In my region supervised visits tend to be very short term so I am not convinced that over the course of the coming years he will not have them on his own - particularly the younger 2. You are right though, I should seek actual advise relevant to my situation rather than looking at what is generally the case.
Of course he might put his foot in it, when I told him I didn't want him to drive the kids around while he had illegal drugs in the car, he told me that he didn't see what that had to do with anything....