Daughter called son half brother....

My daughter is 18, middle son is 16 , and youngest is 14 going on 15. It recently came out that my 16 year old is not my husband's biological son. My husband already knew this. I was raped by my cousin on my birthday and got pregnant... I didn't want an abortion and I told my husband I understand that he doesn't want to raise a child that isn't his. He left but changed his mind a few months later. He absolutely loves our son. We never told him but he found out a couple months ago... And now everyone knows... It's been hard for everyone. My daughter got mad at him yesterday because he asked for the car first so I said yes and she wanted to go see her boyfriend (he can't drive because of seizures). My son was going to play Dungeons and Dragons... Well she has been pissed about it all day and today we were meeting her cheer coach and she said "This is my mom dad, little brother". Then paused and pointed to our 16 year old and waved dismissingly saying "That's our half brother". I know that comment hurt him bad. I don't believe in half siblings unless you are talking about a family tree. It made him cry and how he believes he's no longer part of the family or my husband's son.

Edit: The way my daughter takes to her boyfriends his the highway because he's in another city, and my son is scared to drive on the highway. I know she said it out if anger but it wasn't something to be that angry over. there are plenty of times she got the car before he could.

Edit: I've already talked to her and she just says "I said the truth. Nothing wrong with the truth". She can be vindictive sometimes. That's just how she is. I can't force an 18 year old into therapy.