YOu did fine. I think her "ouch" was more along the lines of oops I messed up, and not that you were correcting her. I'd hope she's professional enough to realize its better you correct her, nicely, than have her call him by the wrong name!
Slightly OT but I used to work in a law firm where we had summer interns. One of the name partners was older, and married to another one of the partners, who was quite a bit younger than he was. They met there, fell in love, and got married. So I was in a meeting with some of the interns, and one of them referred to her as his daughter. I quickly, but politely said, no actually, she’s his wife. The intern was so very grateful that I had let him know, so he didn’t put his foot in his mouth later on!