[Barwench]

Only thing I can add to what pete said is to maybe sit down with your daughter and find out WHY she miss behaves at school, tell her you will always be by her side if not always on it.
Also get her to help you set the house rules, rules she makes herself are harder to break.
Now her mum, thats a hard topic to broach, not knowing all the ins and outs of your relationship its hard to give advice, what I can tell you though is my experience with my eldest daughter father.
He was a nasty piece of work, put me in hospital 3 times, but my daughter still thought the world of him. I never stopped him seeing her, or bad mouthed him in front of her, but I did tell her I didnt like him any more. It took her till her 18th birthday to realise what a bastard he was, and she wanted nothing more to do with him, I then told her all about him.
It took a while, but kids aint daft, they come to their own decisions in their own time, but aventually they see through all the crap and lies, the trick is just to weather the storm till then.