Do I have the right to break ties with my mother?

I want to start with the fact that my mother is not a Muslim, and that I converted to Islam before I got married. My mother extremely hates Islam with passion. She constantly tells me how much she hates this religion. My problem is after a very long time of being happily married to my Muslim husband, she won't stop causing us problems. She is arrogant and selfish and she will take any opportunity to break apart my family. She has always wanted me to divorce my husband and take my children away, and she won't stop giving us problems. She even spat in my face when I told her I converted to Islam. We have been patient, but she just did something so horrible (i prefer not to say) that now I can no longer trust her. I cannot trust that she will not take any chance to hurt me and my family only because she is full of hate to Islam. She won't stop. After this incident that just happened I told her I no longer consider her my mother, that she is not my children's grandmother anymore and have not spoken to her since. My husband and even my children can no longer trust her either and we fear that she can cause us even more pain and problems that this time cannot be reversed. We have tried to work things out with her, tolerated her and tried to give her chances but we are suffering from her. I cannot say all the horrible things she has done to us.