This patient support community is for discussions relating to teen health, including abuse, acne and skin, alcohol and drugs, ADD/ADHD, exercise, growth disorders, infectious diseases, learning disorders, nutrition, piercings and tattoos, teen pregnancy, relationships, safe sex, sports injuries, STDs, vaccines, and weight loss.
You don't mention your age but I assume you are a young person as well. Try to imagine yourself in your sister's situation, scared and confused. Really try to get this understanding, it will help. And then, go and support your sister and her new baby. She needs your love and understanding right now. She needs you to be her ally. Treat her how you would want to be treated. That's what sisters do for each other.
Try not to judge, we all make mistakes.
Good luck.