+bloodlust from the constant battles she had to fight & related conditions. most of it was probably stemming from that & it all just kept building up afterwards. it's kinda like any addiction. you get hooked on something small & eventually you do it so much that you don't get any stimulation from it so you have to move to something stronger just to have a reaction.
i think she got addicted to bloodlust & after the wars ended she didn't have anything to channel it through. So she tried other stuff at the duke's proposal (the drugs, booze, & "handsome" guys). So then she became a blood-lusting, unfocused, alcoholic sex addict. & because of all that she was a psychotic tyrant for 2~ish years & her reputation fell to shit.
so NOW she can't use excessive violence against the asshole like duke Fez & all these other rats because she's trying to fix her image from tyrant-->rightful ruler (mostly so they don't kill her)
Damn all it took was a drug in her drink and men, and that’s how she went crazy? That’s kinda sad