Please seek counsel from a wise priest. You say your mother had an opportunity to become Catholic but chose otherwise. To me, that implies that she is not Catholic. We do not expect non-Catholics to meet the standards of Catholics, especially not those of Traditional Catholics. If your mother violates natural law, ie. has a same sex partner or actively condones such behavior, if she practices what she acknowledges to be Satanic or occultic religion, is grossly immoral in your presence or engages publicly in unnatural vice, then yes, you need to cut the ties and have nothing to do with her. My guess, however, is that this isn’t the case. There is a fine line to walk between keeping communication with her open or driving her closer to Hell. Think of her as your average “nice, but not religious” secular American. How do you treat such a person? Do make sure your mother knows “what the Church teaches” on the major issues. (Put it in those those terms, NOT in “where I stand on.......”). If you wish, PM me as I may be able to assist you if I have more info.