You are doing the right thing for your child. I think it would be worse for your child to be exposed to such a toxic environment. It takes a lot of courage to do what you did. And you are doing ALL the right things.
Of course she will miss him and want him back - that is normal. All children want mommy and daddy to be together. She is still too young to understand the real reason why. Feel good knowing you are doing the right thing and don't be sad.
I think you are so amazing because of the way you are handling this!