BarakaAllahu feekee for the efforts that you all put forth and I ask Allah to increase you upon khayr, sincerity, firmness and humbleness!
My non-Muslim mother-in-law lives with my husband and me. She is a Christian and we do not get along. My husband says that we “stress him out” the way we act towards one another. I don’t want to earn Allah’s anger by treating her mean at times because I honestly struggle with being nice to her, especially since she isn’t kind to me, Allah’s aid is sought! I want her to move out but I don’t want to be mean to my husband by telling him that I want his mother out of our home.
My advice to you:
In your situation you do need to take a “Niyyah” (intention for Allah’s sake), and think first:
What will please Allah?
1- Try your best to tolerate her annoyances, and respond to any disturbing act from her with gentleness from your side. This is how the Quran guided us as in verse 34 chapter Fussilat:
وَلَا تَسۡتَوِى ٱلۡحَسَنَةُ وَلَا ٱلسَّيِّئَةُۚ ٱدۡفَعۡ بِٱلَّتِى هِىَ أَحۡسَنُ فَإِذَا ٱلَّذِى بَيۡنَكَ وَبَيۡنَهُ ۥ عَدَٲوَةٌ۬ كَأَنَّهُ ۥ وَلِىٌّ حَمِيمٌ۬
“The good deed and the evil deed cannot be equal. Repel (the evil) with one which is better (i.e. Allah ordered the faithful believers to be patient at the time of anger, and to excuse those who treat them badly), then verily! he, between whom and you there was enmity, (will become) as though he was a close friend.”
So try your best not to be infuriated and take an intention of making an indirect dawaa to her.
2- You need to aid your husband to be a good son to his mother, even if she is a disbeliever.
3- Your situation even with its difficulties is much better than risking your relationship with your husband and losing his affection. Try not to spoil your marriage.
4-Finally, if you did try your best to please Allah and avoid troubles, but the harm is beyond your tolerance, then you can ask your husband in this case to provide a separate home for you.