"Sorry, I am confusing you with someone else."
OK, but the sentence should be in the past tense. You are no longer confused.
"Sorry, I confused you with someone else."
"Sorry, I got mixed up with someone else."
No, you got him mixed up with someone else.
"Sorry, I got you mixed up with someone else."
In the series Prison Break, Michael who is a white man is asking a black man for a medicine named PUGNUc.
White man: I can't get it at medical.
Black man: Why not?
White man: Because they're already giving me insulin shots.
Black man: You're one mixed-up cracker, you know that?