How do I handle this?

PoundCake

Long story short,

STBXH and I separated in 4/10.  It was not good.  He is an addict.  I filed for custody in 3/11.  I got sole physical custody and  sole legal custody.  He got supervised visits. The county has no one to supervise so it was me who had to do it.  The last visit he had was 6/11. 

After that he just went crazy.  I got threats of hurting me, killing me, etc.  He said he didn't want to see the kids because his hate for me was more than his love for them.  I filed a 24 hour PFA in 8/11.  He calmed down, and there was no contact.

Then he started again with random threats, mental abuse, etc. I just let it go since he is bipolar and I wanted to ignore it.

Now at Christmas time he changed his tune and wants to see the kids.  My kids are almost 5 and 3.  Both girls.  My  5 yo has a hard time with her dad being gone and the last time he saw them and left, she took it hard when she didn't see him after that.

Plus, I'm simply afraid.  He hasn't said anything about the threats except he's changed.  Nothing else.  But I'm afraid.

I want him to be a dad, but I'm afraid of my kids getting upset again if he stops the visits, I'm afraid of his threats (especially with the news lately), I don't know how to handle this.  And I tried the county and there is no court appointed person to be able to supervise.  Yet I hate them not seeing him if he really does want to be a father.  But how do I know for sure?

My kids are my life.  I need advise.