I’m very sorry that you are dealing with something so painful in your family. It’s not at all usual or normal for an older sister to be competing with a sister who is so much younger. I have to wonder why your 17-year-old feels so insecure in spite of all her accomplishments that she pushes her little sister so far away. Did something happen when baby sister was born that meant way less time and attention for her? Can you think of anything that happened three years ago that makes her feel like her little sister is unfairly favored? Sometimes teens create drama to telegraph that they need help. Is your teen’s behavior a signal that there’s something she can’t tell you? Does your oldest have any insights into the situation?
I know you tried counseling but I think you should try again. Even if your teen doesn’t go, you and your husband and the other kids can benefit from counseling. An experienced counselor will try to help you figure out what’s going on so you can start to work on it. Further, your youngest is unfairly taking the brunt of whatever is bothering big sis. She may need some extra support so that she knows it’s not her fault. Working together as a family, you may find a way to engage your teen and to help her.
You made an important first step by reaching out to us here. Please follow through and find a family therapist who can help you get to the bottom of this and repair the relationships in your family.
I wish you well.