I wish I could give you more context but that is what said in the film.
Yes, but in what context? The words were not just suddenly uttered out of the blue. Depending on what had been going on before the words were uttered, they might suggest that the person addressed had been spending a lot of time in bed, and might not have stirred even to contact his mistress. We can only guess, until we know more.
So you just happened to catch ten seconds of the film? Sorry, we can't really help then.
Sir, This dialogue is not related to the story of the movie.
Two police officers while going in the lift talking about the the case. The lady police officer asks this to the male officer and the officer replies that I don't know what you are talking about . I am a married man.
Thus is the scene when that dialogue is spoken. Since, that sentence is irrelevant to the story I couldn't tell the context.
NOt a teacher
I think that should be like that with the context Got up to your new mistress this weekend? I don't know what you're talking about, I'm a married man
Get up to means do something bad.
After all, the meaning is not clear. Does it mean : did he(you) act badly with this mistress?