I'm trying to phrase it in a way that doesn't sound preachy or purposefully trying to rope her back in. That's just going to make her situation worse. Also I'm giving myself some time to let the raw emotions settle down a bit.
I was in a similar situation to hers with adults trying to put extra-biblical legalistic regulations on me as well, but unlike her I knew what the Bible actually said and could defend myself without losing my faith. I'm so thankful for that now. Very thankful. And that is what gives me life and hope every day. I want her to experience that as well.
Basically if people can influence what you think of God, they got you and can shove you around. If they can't, and what you believe is true, you're unstoppable spiritually.