My Mom Has Oral Cancer And She Is Very Weak?

Hi guys I have a question that's really worrying me a lot and living in the uk and mom in srilanka its so depressing that i can be there for her and i struggle a lot while it times get me very moody and angry about life it effects my marriage too.
My mother has lost a lot of weight that it has come to a point you can see the ribs and someday s she talks well and others she struggles a lot, Basically she has her days. She keeps preparing herself for the end and it hurt so much each time i speak to her, I can't fly back home anytime soon as i have an year old son and other liabilities.
She has lost a crazy amount of weight and can;t eat anything other than her cup a tea. She gets very tired and so much pain all over her mouth and can't sallow at all.
My poor mom is also a victim of a bad marriage and so its an added mental stress.I feel so sad i wasn't able to bring my mom to uk just to show her the country and where i live. But she has faith in god and prays a lot.
I really Don't know how i would handle her loss someday, I am going to see her in April and i pray each day that she will be there when i go back home :( She is my life and i never actually got a chance to thank her for this amazing life she gave me and instead i am stuck her all depressed and trying hard to fight my emotions and everyone around me feels i care less of her condition. and its sad how people judge you, Only if they knew the truth and hoe hard it has been on me.Even when i talk to my mom i always try to be strong and never show i am sad to worry her.I don't know guys anyone reading this...PLs give me some hope to hold on to life as i have a lovely son and an amazing husband.
Please give me a genuine answer to this because i have to know.... Are these signs her last dayz???? How long can a person survive with oral cancer??????

Finally... P Lease include her in your prayer...Her name in shami.

Thank you for your time.
God Bless xoxox