Is uttering abusive words about someone who mistreated my mother considered backbiting?

Backbiting is mentioning your brother with what he dislikes in his absence, and it is forbidden. If the characteristic is not in him, then it is slander, which is also forbidden. Whoever has backbited must repent to Allah, resolve not to return to it, mend their heart towards the one they backbited, seek forgiveness for him, and mention his good qualities in front of those before whom he spoke ill of him. As for insulting and cursing in his presence, it is also forbidden, unless it is retribution in kind for a wrong without transgression, for Allah Almighty says: (And the retribution for an evil is an evil like it), and the Prophet, peace and blessings be upon him, said: (The two who curse each other, what they say is upon the initiator, unless the wronged one transgresses). Patience and forgiveness are better and greater in reward.