My(M23) bestfriend(M22) told my girlfriend(m23) the wrong date of my birthday(10 days early), as a joke/prank. She fell for it. Should I tell her?

My gf called my bestfriend to confirm if my birthday was on the 6th or 16th of January(it's on 16th). My evil bestfriend told her it's on the 6th. And he told some more of my friends the same date and made em all believe it somehow. We were laughing about how he pulled it off and now I'll be getting wished by everyone at the 6th, But now... well, when I put myself in my gf's position, I think I'd feel bad or embarrassed. I don't want her to feel bad. She's really caring and was even thinking of what to get me.

Should I tell her? My friend said not to and we can celebrate on both days and make it funny, but her... I just don't want her to feel bad. I really care about her too. If I told her I'd be ruining my friend's plan/betraying and if not... I'd be possibly making her embarrassed infront of me.

What should I do? Any advice or ideas?