Maurycy Wasniewski
Maurycy Wasniewski voted up Veronica Dultry's answer

If you feel you must I'd just be honest about it. Being that said daughter is at least over the age of 20, going forward I wouldn't talk to her about your relationship with her daughter after said conversation. At that point you could be rubbing it in her face which could anger her further.

Maurycy Wasniewski
Maurycy Wasniewski voted up Veronica Dultry's answer

If you feel you must I'd just be honest about it. Being that said daughter is at least over the age of 20, going forward I wouldn't talk to her about your relationship with her daughter after said conversation. At that point you could be rubbing it in her face which could anger her further.