Not much to go on

Here’s the thing, I know practically nothing about this movie save for the last… I want to say five minutes of it. Long story short I saw the ending as a kid and I’ve always wanted to at least know the name of the movie in question.

This might be a made for TV movie, I would have seen this in the late 70’s / early 80’s.

Anyway the scene takes place in a mansion of sorts. A clearly disturbed woman, runs into a padded room in the mansion. She starts attacking the walls with a knife, tearing them up before pouring gasoline everywhere and then setting it on fire. The door of course closes behind her, she’s trapped and is at the window banging on it for somebody to come and get her out. But the only other person is in the car and driving away. So obviously she dies.

Dunno the genre, maybe it’s a thriller. Maybe some psychological horror movie. Can’t say. Been looking for the title on and off for years but nobody knows what it is. So I’d appreciate any kind of help.