ULPT Request: How do I get revenge on my dad's mistress

As the title suggests, my dad had a long-term affair several years ago. I only know the woman’s full name and address.

While my siblings and I were growing up, this woman made my mom’s life a living hell. My dad was barely home, leaving my mom to keep our household together while the affair continued. The woman repeatedly harassed my mom through messages and had two children with my dad. The situation caused constant arguments between my parents and created a dysfunctional home environment that left lasting trauma on my siblings, mom, and me.

To be clear, I know my dad is equally responsible. He was selfish and cruel, and I have confronted him about the harm he caused.

Fast-forward to the present: my parents decided to remain together “for our sake,” and our family recently began building a new house. When the woman found out, she started harassing my mom again. My dad appears to have made her stop, and I believe their affair is over.

Although the harassment has stopped for now, I am still furious about everything my mom, my siblings, and I endured. For once, I want her to experience consequences for the pain she caused.

So, Reddit: what is a legal but unethical way to seriously inconvenience her?

To add: I don't have her phone number because my mom has deleted the messages. We also do not talk to the other 2 children.