To hurt someone's feelings badly

When Lucy met up with her high-school friends after 15 years, she felt cut to the quick because all they could talk about was their children while she wasn't even married

Quando, dopo 15 anni, Lucia ha rivisto i suoi compagni di liceo, si è sentita punta nel vivo perché parlavano solo dei loro figli mentre lei non si era nemmeno sposata

Matilda thinks she's a lady, and when I told her that she was rude to me, she felt stung to the core

Matilde si picca di essere una signora, e quando le ho detto che con me è stata maleducata, l'ho punta sul vivo

When I left him he looked so sad that I felt hurt to the core, so I turned around and comforted him

Era così abbattuto quando gli ho detto che lo lasciavo, che mi ha punto sul vivo e mi sono sentita in dovere di consolarlo

The old meaning of "quick" was "living"; hence the part of one's nails which is below the skin, which still has feeling, is called the "quick"