Your husband and children are your motivation right now, they NEED you to stop dwelling on the morbid side of this thing called cancer. I know it's hard, I've been there PLUS had to deal with the side effects of treatment. I remember crying at the kitchen sink one time, watching my youngest (9 at the time) in the backyard with her father. I was weak from radiation and it just overwhelmed me that she might be left without a mother. But I can tell you that she seldom saw me sad or down, in fact we all worked double time to keep life as normal as possible for her and her sisters.
I'm not trying to be insensitive. I just feel like you're really caught up in the "down" side of it all. If you're feeling this overwhelmed I can only imagine how your husband and children feel. Maybe focusing on how they feel and ways to assist them through this difficult time will help take your focus off the depressed feelings and make you feel better.
Again, please don't take this post the wrong way. You need to vent your feelings and talk about it. But you also need to begin to work on coping techniques that are going to help you and your family through the toughest times that are still to come.
Minnie