Stay. Do what ya have to do. Can you set up some hidden cameras to detail his abuse? It will be a given that he will harass you to make you leave. Maplin had some easy to set up and hide for cheap or try the catalogue store where you write down the item, hand it to the clerk and they pull it from the back or deliver it for you (can't think of the name of the store).

I thought the house was in your name only? And that SD had moved back in with her mother? How many of your children live with you? I find it hard to believe that a mother with a baby and other children in residence, some of whom have special needs, and who owned the house prior to the marriage, has no greater claim on the family home than her husband. Did you discuss his abusive behaviour? Are there no options for a restraining order? If I were you I would begin retrospectively documenting his behaviour. Is your sister no longer able to stay in the house with you?

You've only been married 3 years? He moved into your home with his child and has been repeatedly abusive and somehow he has equal rights and his child counts more than yours? Your solicitors advice sounds odd to me, I would get another opinion. You should go to your doctor and ask to be referred to an NHS counsellor, not only do you need help coping with this and the impact of his behaviour, it will also give you a qualified professional to corroborate your experiences during the marriage.

This is so wrong, Hun , I feel so sorry for you!!!! How is that all possible??? Just tell yourself that no matter what you need to do now doesn't mean this is long term destiny- eg leaving now doesn't mean you will loose the house! Just do now what you fel is the best for you and the kids, one day at the time, one hour at the time! X

I do like the idea of some bad a$$ guys moving in to annoy DH and protect you. Is there anything in your laws saying you can't do this? Fill the house up with people.

Your children going to your ex's is very kind and understanding of him considering he invited you also. Not all exs would do that. Not the ideal solution, but at least you know the kids have a safe and peaceful place to go if need be.

So with the house. I understand DH unfortunately has rights and that the house is considered no more yours than his (though I think your laws suck in this area of divorce), but does this mean you can't sell the house either until his brat turns 18? If you beat him to the punch and sale it out from under him (I suppose you'd have to divide the money?) would it free you from the abusive monster? Would what you get out of the sale as your share enable you to start again, just you and your kids? I think I'd rather lose 1/2 the value of my home than be dead or live in prison. The violence in the house is explosive and I'd fear under the new news he and his SD have rights to it could make this all get even uglier.

Keep in mind this is the UK, not the US. There are differences.
According to what has been posted previously, OP's DH put in a large lump sum of money into this "shared" residence. So it isn't just "he moved in and has ownership" here.

Honestly, both of these people have made a mess of this situation.

OP, I'd die before I shipped my kids off to live elsewhere. I'd move. It is JUST a house.

But it is your house. How old are your kids? You really need a second opinion. He's going to be couchbound for a couple of weeks, right? So he'll be more of an annoyance than anything.

Do not move out. Call the police each and every time he begins to become abusive and have him removed from YOUR home. If SD is there, have the police deliver her back to her BM as she is not your responsibility.