Narcissists commonly cut people off and out of their lives due to their shallow emotional style of seeing others as either good or bad. Everything is black or white to them. If you have seen your mother do this, your fear of abandonment is very real. But you must assess it in realistic terms. If she has already abandoned you emotionally, she truly does not have the power to do much more that could wreak equal or similar devastation.
H/T: Karyl McBride, Ph.D.
Will I Ever Be Good Enough?