My Republic

I'm fairly sure I've started going mad
Dick's right/left brain separation theory seems to be taking it's effect upstairs and I'm changing significantly
I don't know what set me off, but the defenses have gone up and I've started lashing out at the people in my house
It all started with my sister's interest in purchasing a dog. Now, don't get me wrong, I don't really have a problem with dogs in a short term capacity, they're attentive, energetic, all that jazz, which is fine, I just don't want one anywhere near my living space, they shit everywhere, make the house stink and break stuff (Most of the things I own are quite fragile).
My main aversion to a canine in the house however, was my cat of 17 years. I don't care how small or 'quiet' any breed of dog is, a cat of that age simply could not handle such a large intrusion of her space.
Long story short, I fought hard to block this dog idea and I think I upset the parties concerned.
This, however, isn't the bad part, usually in a situation such as this I get a sinking feeling of remorse and eventually say sorry for my actions, this time however, I felt nothing of the sort, and continued on my rampage.
I'm sick of people taking things without asking, assuming that doing something wrong will be all ok, should I continue to overlook these things? Or deal out some brand new justice?
Lets hope I'm not in this kind of mood for much longer, this only happens once in a blue moon and I don't care for it.
Split-brain is becoming very real to me, and I'm worried that I like the new me.