Let her talk and rant. It helps her blow off steam - being a teen is rough enough, being a teen who feels she's being treated like a little kid is maddening. Looking into things that interest her, allowing her to chat with some 'net friends, and giving her some responsibility (not just chores) would help her feel more valued.

from our Rose: Elaine sounds strong in your group - trying to fight with her makes your body ill and exhausts you. Acknowledge her strengths, let her know you value her contributions and accomplishments, and you can build a relationship where you aren't at odds with one another.