What an idiot. I'm quite sure Heidi would be much happier in a colony, even if it's outside, than dead. It's unreal that she would rather kill her.
Maybe next time you talk to her you should just forgo the "kinder" word of euthanize and just ask why she would rather kill Heidi than allow her to live a long happy life.
There are only two rules at my house: House rule #1. Cats rule. House rule #2. See rule #1.