Is there any way I'm wrong here?

[defence18]

While everyone else here is correct, anyone at the table has the right to request to see any hand that is active at the end of the river. IOW, any player could have asked to see either your cards or your opponent's. Also, like others have mentioned, since you voluntarily showed one player, all others have a right to know.

I'm not saying it's right, that's just the way it is.

[Howard Beale]

This happens ALL the time. It's not 'proper' but it happens ALL the time. If anybody complains you have discovered the nit.