Yeah, she's gonna defeat the Dad thanks to the power of love (and horni) from Kotaro.
That said I would have loved if Kotaro went full "darkness" on the dad, summoning the most awful animals and bugs. That the "salaryman normal guy" is just a persona he created in the school to blend with the society and in reality he's still an abused child with heart full of hatred. And that not only Tae opened her heart to him, he started doing it too, even if he didn't realise it before.
But hey, this is not that kind of manga and I really hope for a fun and fluffy ending!