Since you volunteered at the DV shelter you know that those working there do not judge. They will do everything in their power to keep you and your children safe.
At first I was ashamed that I had gotton myself involved with my exabf, I knew that I was smarter than that, but, I did it, so I had to pay the price. I learned that the more I reached out, the stronger I became. I also learned that most everyone I blabbed to either had a family member, a significant other or friend that was going thru exactly the same thing that I was.
Please reconsider going to the DV shelter, your mother is going to be useless in protecting you and your children.
Safety first, this man cannot be trusted, he will pounce again.
Sending hugs & support your way.