I got my friend into trouble. How do I square things with him?

Six months ago a friend of mine and I did acid and smoked pot at a friends house. I wrote about it in a blog I was keeping at the time, talking about college experiences and things like that, but I carelessly included his full name. Just a while ago, his parents googled his name, discovered my blog, and flipped. Now he's pissed because I posted his name online and got him into trouble with his parents, who are also pissed at me. We're rooming together next semester, so I've got to fix this, with both my friend and his parents. I realize it was stupid and careless, but how do I square this thing with my friend and his parents?