roula -
I am sorry you are going through a heartbreaking time. I feel your pain and my heart of all hearts goes out to you. I lost my father about 4 months ago to liver cancer and it was an emotional roller coaster for the last 2.5 yrs of care giving so I know exactly what you are going through.
Do what you can to help yourself process your emotions at this time - talk to girlfriends, close family members, church members if you know any or a counselor, and journal. It's important for you to cry it out, talk it out, write it out.
The worst you can do is bottle up the emotions or walk this journey by yourself without reaching out to others. It's ok to feel the emotions you are feeling, but try to work through each emotion so it doesn't get the best of you.
If you believe in prayers, make good on them to bring you comfort and strength. Truly, there are no "right" ways to handle your grief, but there are healthy ways that will strenghten you in hope, courage and strength.
Please know that there are somethings you just can't control, but the best thing you can do is just be there for your mother and keep her comfortable. At the same time, don't forget to take time for yourself as selfish as it may sound at this time - you must take time out to recoup so you can be the greatest single mother that you are and to allow yourself to put things into perspective.
I pray that you will find comfort and strength during this challenging time.
God bless you.