I'm sorry Distressed2010, but it sounds like you are the only sane one. No, it's not being aggressive if you are speaking carefully in a regular speaking tone -- asking basic direct questions in order to understand the situation. I am sorry to hear about what your mom has had to endure. It sounds like a difficult situation where she is being taken advantage of. I know I am often mentioning literature, but I have found this book quite helpful:
http://www.amazon.com/Dance-Anger-Ch.../dp/006091565X
Sending good wishes your way... for a calmer, saner and more understanding environment. By all means, stay assertive, be true to yourself.

Elana