She must have some ulterior motives in mind, prodding his traumatic past like this, making a big mockery of it, of him, as if intentionally reopening old wounds left by his mother.
Whatever her motives are, I hate women who intentionally press people's buttons like this. She just got dropped to 'least favorite daughter' on my list here.
Well he didn't necessarily 'lie' per say, it depends on weather he sees that woman as his mother in the first place.
It could be that "his mother" didn't abuse him, but the woman who gave birth to him did.