I know that things feel like the end of the world right now, but if you hadn't helped your sister like you did, it might have been the end for real. Please don't second guess your efforts, I'm sure you did what you knew to be the best you could at the time, and it worked.

You aren't responsible for her problems, nor how she does or doesn't handle them. We all go through events and then rearrange our plans because of them. Keep on being the great big sister you sound like