Would some one you trust like your mum, or dad or some one close sit in on the visits, then you don't have to be in the same room as him.
I know its shi@ but even though he is a fulltime prat, the courts will give him the rights as a 'dad'.
Get the csa involved make him pay maintaince, my ex had a son and his ex got the csa involved so he would pay maint which he was anyway, but his ex moved without telling my ex, and the csa would not give out her address so he never saw his son again, (my ex died 2yrs ago) he tried to be a good dad but wasn't given the chance.