Starting to scare me with the control

How about when a mom tells their 35 year old daughter that if she cuts her off due to all the whack toxicity and control she’ll try to ruin your marriage and start showing up at your job? I do not need this level of crazy in my marriage and i am beginning to get scared. I believe her mental illness is taking a turn for the worse. I just want some boundaries. And now i’m being threatened.