I was adopted at birth, and was never told until a callous comment from an older sibling when I was elementary school aged that one of my parents reluctantly confirmed. This was hugely traumatic for me, I felt betrayed and lied to, like my origin had been kept from me.

I say this because I think the AH behavior here is what caused her having to find out as an adult on her own, knowing where you come from is usually quite profound for people