I wish I had the words to take your pain away. I really do.
My dad died of colon/liver cancer just over 12 years ago. I was 21, my brother 17. It was very very rough.
Please don't feel like you need to be strong for your kids all the time. It is ok to break down, to cry, to scream, to get mad, to show rage. It is ok.
My dad died on November 10, and about 3 weeks later, my mom, myself, and my then fiance turned on some of dad's favorite music and we sat in the kitchen and cried and laughed and reminisced.
Healing is a long, LONG process. 12 years out and I still have really bad days. Don't let anyone put you on a timeline.
I am so sorry for your loss, for your kids loss....I will never understand why God takes those that he does when he does.
Rest in peace, to your husband, and hugs and prayers for you and your kids.