NTJ. I would never call my brother's wife, or my sister's husband and get after them. His sister was way out of line and if my brother or sister did something like that to their spouse I would tell them they were wrong.
Have your parents take you to the courthouse to get an anti-harassment order. After it's been served, if she tries to contact you call the cops. Her poor life choices (other than putting you up for adoption) are not your responsibility to fix.