It's too bad you couldn't have adopted your SIL. You would probably have been a much better mother to her than your MIL ever could be. If I were in your SIL's position, I'd probably be one fucked-up kid right now having to deal with a parent who essentially prevents you from having any kind of a life and then doesn't appreciate all the hard work and energy you've spent doing what they've told you to do. And seriously, 8am-6pm, six days a week? That's essentially a sixty-hour work week. More really, since like you said, there's all the homework and other activities she's been pressured into doing. Most full-grown *adults* don't put in that many hours of work in a week. I'd want to sleep all day on Saturday or Sunday if I were that overworked, too.
I hope your SIL doesn't go off the rails once she escapes to university, because it sounds like she's a wonderful, smart girl who doesn't deserve all this crap from her mother. And having toxic parents can easily make an otherwise healthy, well-adjusted human being develop into someone who is... well, not.
By the way, how old is your SIL? According to Wikipedia, sixth form is usually from sixteen to eighteen. I'm not really familiar with how British schools usually work.
). They most important thing is her being able to put her mom in perspective as not so great a mom on that point instead of trying to fix herself to live up to impossible standards.
