I also believe journaling is important. And I understand your need for privacy. When I started writing my thoughts down here concerning the abuse I recieved as a child, I knew it would be read by many people. That is why my user name is used and I do not use my real name. No one but me knows of this now, other than my mother, but I want it to be private, as far as, to people who do know me. Another thing you could do is change your user name and set your controls to not show when your on-line. That way you would have a bit more privacy here.
As for your writings at home tell him you stopped because of his actions, but don't stop writing if it helps you. Find a really good hiding place or do it on your computer and put a password in that he does not know.