Brutal, it's hard to control that. I used to have those fits of rage (I still have them today) and just like you I would break valuable things, like a television that my father had bought, luckily he was able to replace it on time under warranty, but what I couldn't escape was how he punished me, I also unfortunately broke a netbook that the government gave me. It's hard to control myself, but luckily I can control myself a little better now (although those attacks still come to me)