Have you spoken to woman’s aid either by phone or their online chat? They can help you with this. Do you have a safe place you can go to – a friend, a relative, a hotel? Would you go to a refuge? Step one is having somewhere safe to get to.
As for the threats about getting you sectioned and your pets, they love to throw these at us. Hopefully it’s all hot air as they use them to intimidate us (and boy does it do that) but many don’t follow through, that said you must keep safe and keep a log of his comments and/or report to the police if you want to.
Leaving is a journey in itself with many ups and downs, but it’s worth it. Good luck x