What will happen?

[littlegreenlight1]

DP found out through a very reliable source yesterday that his ex, mother to his two children, is doing something that is completely unacceptable for a mother to do. It's drug related and I ain't talking smoking a spliff.
He is getting confirmation on whether it is true (but she has previous, not for many years, but once an addict?) and then he will confront her, kindly, because if it's true she is in a world of shit.
What will happen then? Should he tell her he wants the kids (he wants the kids) - should he go to social services?
Never dealt with anything like this in my life and just want to help him - and her really - and most of all the kids.

You could go to SS but unless she's neglecting the kids it will make no difference.

I knew someone in a similar situation, drugs and spells in prison for petty crime and a 10 yr old with very obvious learning issues as a result still weren't enough for him to get even an overnight stay.

They even had to change solicitor because the previous one started to believe some of the lies the mum was spouting and told the dad she'd be scared of him too!

She will totally deny it, kids are fine because she packs them off to her sister at every opportunity.
I'm really worried now as person that told me yesterday is now back tracking and saying it might just be rumours...I mean obviously it's better if it is, but I suspect it's true - how can he prove it if she lies?