Please do not take this the wrong way seeker1950, but I've been where you are, and you are about to take the most arduous journey in your life. I won't sugar coat anything for you, as I don't believe in doing that. You are losing one of the most important people in your life, and there is little you can do or say about it. Right now your mom just needs to know that you "love" her no matter what the circumstances were when you grew up....it doesn't matter anymore. Let it go. Spend as much time with her as you can, and make the most of a sad situation. We all go thru that door eventually.
Tell her you love her everyday and make sure she knows it and hug her often. It's a healing concept for both of you. I
didn't get to do that with mine. She committed suicide six weeks after my younger brother died. I never got to tell her good-bye or that I loved her in spite of herself. For me there will never be "closure". You don't want them to linger on in that kind of pain, though, either. My mom had terminal cancer too. Breast, then spread to her lung, and I think to her brain. She didn't last too long. With liver and brain cancers, the most you get in reality is 3 months. I haven't known anyone who lasted longer than that. They are the most vicious of cancers, and the most painful.

I wish you peace and comfort for you both. You will need her to talk to you seeker. Pls. for your own sake, just sit and be there for her. It will help you in the long run. Each day you have her is a gift of time from God.