What about your father? It sounds like you have put all your eggs into one basket and it's not a basket you control. You need to make your own life, your mother is supposed to be your mother, not your best friend. My mother died when I was 3 so I had a great deal of trouble worrying (as you're doing) about what would happen when my father died. Fortunately I had a good therapist and husband and we straightened it all out. I recommend you not keep leaning on your mother in this way or you will make it extremely difficult for yourself when she dies.