Whirliwig,
good on you for being honest, and admitting you need help, you're right, violence does breed violence,
this article has some great explanations, as to why children are aggressive and how to stop it.
Helping children with aggression
as you say yourself, you need to learn some ways to deal with your anger so you don't lash out in that split second. Anger management, parenting classes, (there are some on the same website as the above link, which have great emotional support for parents,) meditation would also be great as it can help you to 'watch' your thoughts and feelings more closely, so that if you notice yourself getting angry, and feeling like hitting, you can take a time out yourself, sit down, and breathe. although this is easier said than done when your kids are fighting and you need to intervene,
I also recommend a book called, 'when your kids push your buttons,' which explains, how when our kids make us angry, it has roots in our own childhood and how we were treated.