There is definitely something not right about him and I would be watchful to make sure he does not have a detrimental effect on your children. I could not even guess what his problem is since he seems like he may have more than one mental health issues going on. I know the chance is probably slim but do you think you could convince him to see a doctor or therapist?
I think you should talk to a therapist as well so you can understand why you let a man like this into your life. Your therapist can also give you advice on how to deal with this man.

Protect yourself and your children!