I think we all struggle with this at some time or another. However, there is an underlying principle that is very important to the subject and that is charity.
To practice charity is to remain peaceful even in the face of unjust comments. Someone very close to me, who is older and feeling the effects and loneliness of aging and ill health has been very difficult to deal with. Emotionally, I find it a challenge. But charity requires me to be tolerant and loving in the face of that which is thrown at me. I’m not always good at it and when I fail and lash out, I raise the issue in confession. Is it grave (mortal) sin? I think it is situation-dependent and when in doubt we owe it to God to speak to a priest about it in confession and to seek counsel. Many people don’t think to use confession as a way to get counsel, but it is very helpful in this regard. If you are not aware of whether or not it is mortal or grave, then it obviously cannot be. But if you are suspicious that it is, you have an obligation to seek the answer.
There are other circumstances as well. I go back to my teen years and remember all the difficulties associated with developing my own viewpoints and the chasm that begins to build almost naturally between teen and parent. I still adhered to things that my parents taught me, but was troubled by something that may not have meshed with my values as a Catholic. My parents grew up in a different age and one of my parents had difficulties with people of color due to a bad experience as a child. Even at five years of age I would grow angry if I had heard an uncharitable label thrown at such a person. This was God telling me in my heart to not follow this. But, I still have a duty to follow the way that Christ taught - never with a stick as my sig implies.
However, in all matters that do not conflict with Church teaching, I had an obligation to honor my mother and my father, even when I didn’t agree. Contributing around the household was important. Even when one of my parents showed lack of communication skills and maybe communicates with all the dignity of a bull in teh china shop, the Lord calls us to show charity and look for the meaning of what they are trying to say, not how they are saying it.
Cursing at your parents for any reason is obviously showing not only a loss of charity for the moment, but does not honor thy mother and father. This to me sounds like a grave sin by a child against that commandment.
See if this helps. Scroll down and if you find things on this list, then I strongly encourage you to talk to a priest. Don’t just confess the sins, talk about the attitudes or things that led into the dispute, but without casting judgement on your parents, if that is the case. If you don’t know how to handle yourself in a given situation, ask Father for help so you know for next time and if you struggle with it repeatedly, find a priest you can continue to work with so if you fall, he can give you new words of wisdom. Don’t hide a “habit” from him, if it should rise to that level.
Most of all, never lose hope - it is the seed of the devil and there is nothing more that he would like than for us to fall into hopelessness and depair, rejecting God’s love and mercy. This is called a sin against the Holy Spirit and the worst kind of sin. Read abou the acts of charity in this link as well.
2heartsnetwork.org/examination.htm
EDIT: Well, the Acts of Charity aren’t listed in this link so if someone can find the list and an explanation please list it here. In the meanwhile, I’ll look again.