All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Dear questioner, do not deprive yourself of the reward for an act of worship because of someone’s ill-treatment towards you and bear in mind what Allaah The Almighty Says (what means): {“Repel, by [means of] what is best, [their] evil. We Are most Knowing of what they describe.”} [23:96] Furthermore, Allaah The Almighty also Says (what means): {“And not equal are the good deed and the bad. Repel [evil] by that [deed] which is better; and thereupon the one whom between you and him is enmity [will become] as though he was a devoted friend* But none is granted it except those who are patient, and none is granted it except one having a great portion [of good].” } [41:34-35]
Hence, you should treat her nicely, even if she misbehaved and treated you rudely, and you should do this for the sake of pleasing Allaah The Exalted. Moreover, by doing so, you are fulfilling your husband’s rights over you and maintaining your ties of kinship. It was reported that a man went to the Prophet, sallallaahu ‘alayhi wa sallam, and said, “O Messenger of Allaah, I have relatives with whom I try to maintain relations but they sever [the relation with] me. I treat them well, but they treat me ill, and I am kind to them but they are harsh to me. The Prophet, sallallaahu ‘alayhi wa sallam, said: “If it is as you say, [it is as if] you fill their mouths with hot ashes and there will always be with you a supporter from Allaah against them so long as you do this.” [Muslim]
Allaah Knows best.