Hi stressed. Can I suggest you keep notes on everything. And email the sw today stating that you need her help as your h is refusing to leave. I would be tempted to email h too and say I have been asking you since x date to move out as our marriage is over. Firstly to appease ss and secondly as evidence to the court as to when you split up when he tries to take half the equity in the house. (Believe me he will do this).
If he gets abusive in any way call the police. Do not hesitate. Can you log with the non emergency line today that you are asking your husband to leave and he may become abusive so it is on record and you are a high priority.
Have you explained the situation to his parents? Have you told them that his refusal to leave will lead to the continuation of ss involvement. It is likely to ultimately lead to him only having contact in a contact centre thus meaning they may not have any contact at all. Would this motivate them to help?
Ss will keep extensive notes. I suggest you do too and email ss regularly to keep an audit trail. Do not defend your husband in any way. Tell them you have asked him to leave many times but physically you cannot remove him from the property which is in your sole name. Ask them can you legally change the locks and remove his possessions. Put that in an email to them today. Ring the police and ask them if you can legally remove him. Document their response in the email to ss. This will evidence that you are doing something to remove him, not just having a fun weekend with your husband hoping ss will go away. Call women's aid and ask them how to remove him.
In the meantime if you have nowhere to go, stop washing, cooking etc for him. Do not live like a family. As a drug user etc ss will not take the risk of something happening to the children. They will not be 100% sure that it is him refusing to go or you wanting to be with him. If he won't leave and you have asked him to go then they are justified in saying you cannot protect the kids from him.
Could you stay with a friend?
Good luck op, ensure you evidence to ss that you are protecting your children and that your marriage is over. Ask ss if they will arrange contact via a contact centre for him explain you want it to be supervised by someone other than yourself. Your husband is clearly delusional if he thinks ss won't remove the children.