OW is trying to be coy...OW is trying to get under 18yo skin so that maybe 18yo and his old man will get jealous of each other.
Sick...but most OW are this way. They want attention, and they don't care how they get it.
She's trying to be 'cute'....she's not being cute, she's being perverted.
Either she wants the old man...or she wants the attentions of someone closer to her own age...the 18 yr. old.
This is where you, Sun, have to step waaaaaay out of the picture...and do nothing, say nothing, plan nothing...nothing.
OW is lighting her own keg of TNT....you won't have to help her have it blow up in her face...she'll do fine on her own.
There is no way on this earth that your son will ever look at her and like to think of himself as 'her boy'. I'm sure he's as embarrassed by her remark as you are angry about it.
Women are angels. And when someone breaks our wings, we simply continue to fly...on a broomstick. We are flexible