Sarcasm is a wonderful thing, that is, when it's used in good taste. Your "joke" was made in poor taste.
Actually, I don't think he was joking.

It's not like she's going to live for a long period of time when your brain damaged. They say shes 'suffering' but how do they know that for sure? She's not a vegetable. She can move, look around and blink. She could be aware of what's going on and they just want to pull the plug and let her starve to death.
She moves around and looks around involuntarily. She is brain dead, and science has pretty much proven that she has no idea what is going on. These are all involuntary movements. She doesn't smile anymore, she moves her mouth. She doesn't look at people, her eyes just happen to move in that direction.