First off, let me send you a great big cyber hug.
(((((((((((((((T.))))))))))))))
I know how hard losing one person to cancer is, my mother died many years ago of colon cancer. Facing the possibility of losing two family members makes it so very much harder. My heart goes out to you. I will put all of you, both cancer patients and family members, into my prayers.
You have the responsibility of taking care of your children. Please consider the "oxygen mask" advice. If an airplane loses pressure and the oxygen masks come down, parents are told to put theirs on first, so they can be able to take care of their children. So too, you have to take care of you so you can take care of your children. Make sure you are getting enough rest, eat healthy, all the things that you need to do to make sure you are strong.
If this is overwhelming for you, consider getting some sessions with a therapist to help you learn to cope. That's what they are for, and helping people cope with difficult times is usually covered by health insurance. It's called adjustment therapy. If you are a person of faith, consider talking to your spiritual leader/minister for guidance and support. Reach out for any resource that is offered.
Losing anyone is difficult, even after you have become at peace with the loss, there is always a "hole in your heart" where you miss them. But, they will always live in your thoughts and in your love. They will be alive to you. I hope you can take comfort in that thought.
Peace,
M..