What does Islam say about abusive parents? The children get mentally affected and traumatized and, sometimes, they yell at them in retaliation. Is that allowed?
Parents are not allowed to do injustice against their children or any of them. Being abusive with people is not an Islamic way to behave. Yet, if the parents or any parent becomes abusive, the children are never allowed to yell at them under any circumstance. Allah says in Quran about treating your parents: And never tell them Uff (any word of annoying) and never raise your voice at them. (17:23).
There is no question of retaliation we deal with our parents, no matter how bad might be. Even Kafir (disbelieving) parents who insist on their children to become disbelievers, must be treated in nice way. Allah says in Quran (If your parents strive to make you a Mushrik (polytheist), don't obey them, and deal with them nicely and kindly)(Sura 31, verse 15).
Wassalam.