Husband does Kufr - Clarification

Assalamu Alaikum brother, I have an issue regarding marriage. My husband was making a lot of kufr and I contacted an Imam in Peterborough to ask if my Nikah was still valid. In short version he told me that our Nikah is unvalid and if we wished ti remain married we needed to renew our Nikah. Which I gave not done and insted I moved out with our 4 young children. As I now believe that we are no longer husband and wife. Now I have to work and I need him to watch over the children for couple of evenings and every other weekends. That means that he will come to my house and sleeps in my boy's bedroom. I cover myself infront of him and don't really even talk with him. He is just around the children. Is this allowed? I have no support here no families nobody and my children are 3,6,9 and 12 so very young. I also need to work if I wish a future with a job as I have been away from work for 6 years now and I can't receive any benefits do to this. He's situation is still unsure as he does pray but unfortunately when he gets angry he makes kufr again so it is a circle for him. I need to know what should I do as to me my religion comes first and then my children Alhamdulillah. Please advice me please!