Leave

It takes all of your willpower but you turn away from your sister and walk out of the room, leaving her behind. When you come out of your bedroom an hour later, she's gone.

You don't see her again until Mother's Day. You don't talk about what happened. You never talk about that day again. You barely talk, period. Sometimes, in a crowded room the two of you will share a look or a touch and you'll remember that moment. You always know you made the wrong choice.