OP, did you intentionally cause damage or whats the deal? 25 cats or 10 dogs? 15 kids?
There is no reason to lose any of your deposit unless you have something out of the ordinary or you intentionally damaged something. Everything else is wear and tear.
2 rules of thumb.
1st) Don't pay the last 1 or 2 months rent, so you don't get scammed. Better to let the landlord take you to court then the other way around. Good luck collecting money even on a lawsuit you win!
2nd) When you give the keys back you collect the cash at the same time, simple. Companies typically won't do this so you need to think twice about who you rent from.
Don't be a sucker!! Of course the landlord is mentally unstable. If I can play dumb for a couple days or a week and pocket 50k, why not?