Sorry you've had to deal with this. I had a similar situation about 18 months ago, and I am so happy I terminated. The child was hurting other kids, and hit me in the face with a truck, leaving a welt on my cheek.

Unfortunately, the parents didn't see it my way, and the mother smeared my name all over my small town. She wrote a longwinded letter and posted the link to it on a local Facebook group with over 5 thousand members. :O Lucky for me and my family, it didn't seem to slow my business down any.

I hope the parents don't give you any grief, and for what it's worth based on what you've written, I think you've done the right thing.