Just because he explained why you're wrong doesn't mean he was "mansplaining". You were wrong. You insisted you were right but everyone at our table cringed at how wrong you were. As soon as he politely pointed out that you were wrong, and why you were wrong, you shot back with "WOW, Thank you for MANSPLAINING it to me".
This word has got to go away. Every time I've heard it used in public it boils down to "someone with a penis refused to let me be wrong. How rude of him!"