Is it a normal reaction to confirm a false accusation after being accused too much?

[Anonymous]

My friend's been dating her boyfriend for nearly 1 year. The guy's mother hates her because of what supposedly her mother did several years ago. Her mother supposedly cheated with her now ex husband. So since her mother is a homewrecker, she's accused of being just like her mother. The woman has been repeating the same ''you're just like your mother many times'' and tried destroying her reputation that my friend got tired of it.

Recently my friend replied with an ''Yes I'm a sloot like my mother. Yes I'm a homewrecker like her. Maybe your husband was a cheating loser after all and he needed a better woman. Yes I've been with many men. Yes I'm all that. Happy now.'' It's false but that's her new reply if that woman or someone else says the same thing again. She'll say yes to it to shut someone up. It seems to be working.

Is this a normal reaction? If you're falsely accused of something for too long (just because your parents did something), you get tired of it to the point you confirm it's all true.

[Guy13]

Don’t you know Guys don’t have the attention span to get through Masters level thesis that you wrote 😉

[Asker]

The point is my friend doesn't understand what does whatever her mother did has anything to do with her nor why does she have to pay the price for it.