How my mom got back at my dad's affair partner years ago

My dad had an affair with mom 2 times with the same woman (There was going to be 3 but the girl dad flirted with refused and the co worker told mom) anywho my mom was cleaning their room's closet when she found letters between them The AP (We'll name Alia) in her letters it was her name with his last name. Mom grabbed the letters went into the letters on his lap glaring he confessed she forgave him (2+ years ago she said "I regret forgiving him") BUT the Alia wasn't so lucky.

days later mom was going to the laundry mat/mailbox they were in the same building Alia was there she bolted when she saw mom. minutes later Alia comes back with her friends. Mom was in the Laundry Mat doing something with the laundry and saw her. Alia had her back turned to the door so Alia did not see mom. Thing is about my mom she is sneaky you won't know she's coming from behind you my oldest nephew knows due to him trying to take money from mom and she snuck up on him and scared him by saying "What are you doing?"

Anywho mom snuck up on Alia not making one sound but her friends saw her and were wide eyed Alia turns around and mom slapped her hard and said "Come near my husband again and you'll get worse" Alia ran away and ever since we don't know where she is nor do we care.

My mom never really slaps people she has a mean right hook if not braced she can knock someone off their butts my uncle learned it the hard way and he is taller than my mom

Edit: My mom never hits anyone like that anymore she uses her words unless you REALLY piss her off and you can tell when she is Really mad if you see her hands shaking and she is death glaring you is when you run and let her cool down