Hi
I am sorry that you are having to go through this, it must be really hard.
I have not been in your situation but If I was I would do everything I could to protect me and my child. Right now your baby does not understand or know what is happening or that his dad has been abusive to his mum. I am sure when he is older and aware he would understand steps that you took to ensure you were both safe.
I hope this helps, and you are able to get the support you need.