The SS will be in your life constantly if you take this guy back, they would be in yours and your children’s life for at least a year, the kids would stay on the ‘at risk’ register, or even go on it if they aren’t now. Your BF would be all sweetness and light when the SS were there but he’d probably give you a hard time when they went away, it will all be your fault for telling the police I’m the first place, blah blah blah.
Also, can I ask what drugs was he on? If he moves back in with you then would he be happy at financially looking after someone else’s kids?
Please have a serious think on this for another few months and I think you’ll feel very different, you have to ‘get over’ him properly and then you’ll feel different towards him, whilst it’s great that he’s doing things to change his life but he may only exhibit these changes with a new woman, you’ve already accepted some of his bad behaviours and he knows this, he knows that your going to be scared of SS finding out about more violence, if it happens, so if he does move back in and hit you then your more likely to keep it quiet and you will have to ask your kids to lie which is not good at all, this will cause anxiety for them and anxiety is bad for adults, never mind kids, he’ll have all the power over you and your kids, is this really what you want? I don’t think it is, also from what your asking then it sounds as if your boyfriend would stop all these changes at the drop of a hat, if he couldn’t move back in with you.
The SS will now be aware that you’s have been back in touch and that’s not good at all, who knows what they’re going to do next, the more you keep your BF in your life then the longer the SS will stay in it, you don’t want that for your kids I’m sure.
I also agree with other posters about drugs being no excuse for violence, violence is either in you or its not, drugs shouldn’t change that, what worries me is if he was addicted to heroin then he may hit you when he can’t afford it, seen as heroin is a physically addictive drug.