@xx200xx I have not RTFT, only your own posts, but it sounds very clear that you have taken actions that are necessary and appropriate in order to protect your child and yourself.
While it is natural for you to be worried ahead of any sort of court case, it really sounds as though you have a very strong case. Think about what would be the best outcome for your child, and then think about what a judge would do, if they know they cannot change him nor change you, they cannot expect either of you to be perfect, but they want to do what is best for the child. Presumably they will hear from the social worker and the domestic abuse worker.
I do not know the system, but to me, having read some of the key points in your post, it seems inconceivable that they would offer him anything close to joint custody. It seems much more likely that they would give you full custody, with some sort of contact arrangements, probably supervised, for him. Look at the facts: you are the primary carer, the child is too young to talk, and there is strong evidence that he is guilty of domestic abuse, which means the child could also be unsafe with him, at least in the eyes of a court.
You are in effect a single mother, with very little family support, and you are doing your best to care for your young child, whom you love, whereas the father has shown that he is willing to harm family members who are vulnerable. I have to believe that the most likely outcome, by far, is that the judge will see that, and you will win your case.