I can’t tell if it’s you leaving or your colleague.

If it’s your colleague, then do your job and count down the days til they are gone.

If you are leaving (especially if it’s because of the colleague) - weigh the pros/cons of saying something to a trusted admin. Do you have documentation or proof that shenanigans are harmful to the school? Tell someone. But only if you have another gig lined up and burning that bridge won’t ruin your career. Too many of us are told to keep our mouths shut when we leave toxic situations and I’m tired of it.