This isn't just about they did to Thomas, and it isn't just what they did to everyone else they've fucked over. It's mostly about what your father did to you and THAT'S why murder is suddenly an option. Even after Thomas got killed, you painted your dad as a saint. You still blamed what happened to your mom on Jarod, even though he was a little kid AND a victim. This is your rage from remembering how your dad abused you talking, and you're totally right in feeling it, but you have to actually move on before you can move on from here.

For now, chill the fuck out and take your time dealing with this, because this isn't something you wanna half-ass. If you're really that hung up on justice being served, you'll find a better way to do it, LATER. Work on yourself first.