Our Gemara on Amud Beis, cautioning against allowing a young child to be taken care of family custodians who have a stake in his inheritance, relates a macabre story:

תַנְיָא: מִי שֶׁמֵּת וְהִנִּיחַ בֵּן קָטָן לְאִמּוֹ, יוֹרְשֵׁי הָאָב אוֹמְרִים: יְהֵא גָּדֵל אֶצְלֵנוּ, וְאִמּוֹ אוֹמֶרֶת: יְהֵא בְּנִי גָּדֵל אֶצְלִי — מַנִּיחִין אוֹתוֹ אֵצֶל אִמּוֹ, וְאֵין מַנִּיחִין אוֹתוֹ אֵצֶל רָאוּי לְיוֹרְשׁוֹ. מַעֲשֶׂה הָיָה וּשְׁחָטוּהוּ עֶרֶב הַפֶּסַח!

As it is taught in a baraisa: In the case of one who died and left a minor son to the care of his mother, and the heirs of the father say: The son should grow up with us, and his mother says: My son should grow up with me, the halakha is that one leaves the child with his mother, and one does not leave the child with one who is fit to inherit from him, i.e., the father’s heirs. An incident occurred, and the boy lived with his father’s heirs, and they slaughtered him on the eve of Passover. 

There are different versions of this story.  Some texts (Tosefta) have Erev Rosh Hashanah, while the Rosh’s version is Erev Harishon, presumably to state that they were so overcome with jealousy, they killed him right away.  The most logical assumption is that the original text was Erev Pesach, and so as not to give fuel to the Gentile blood libels, it was emended to Erev Rosh Hashanah.  

In any case, while we might read this and shudder and gasp, familial conflict over money is real, and the Gemara is pragmatic about human nature. I am aware of a domestic violence situation, decades ago, in a frum household where the father murdered the mother on Erev Yom Kippur.  There also was a famous case brought down in Tosefta Yoma 1:10 where one cohen stabbed and murdered another over who would get the “zechus” of performing the avodah (probably the ketores, and may have been on Yom Kippur, but not totally clear from Tosefta. Also see similar story in Mishna Yoma 2:2) 

People are most dangerous and most inhuman when they deny their animal capacities, and think that they are incapable of murderous cruelty. Erev Yom Tov is a time of tension, and for many, traumatic memories of past family of origin conflict.  We know that Satan looks to disrupt moments of potentially highest holiness with the depth of impurity.  On Erev Yom Tov, let us be careful not to commit true assassination nor character assassination.  Take a deep breath, go for a walk, and have a bite to eat so you aren’t irritable.  Be so, so careful not to deny the early rumblings of rage in your system.  Face it, you can have animal rage.  Do not deny it, so you can find a way to deal with it.  And, please, please forget bringing something up “right now” because it is “for the principle of thing”. It can ALWAYS wait until after Yom Tov.