It breaks my heart to think his family cares more about him than my kids welfare.
I'm sorry that this has happened to your family. It appears that his family (brother) is in denial about the addiction to alcohol and the turmoil it has caused your immediate family. You won't be able to change their minds.
It is wiser to spend your precious energy on taking care of yourself and your children. According to your post, you are on the right track.
I agree with Alice that you may find Alanon meetings and Alateen meetings helpful to your family as you recover from the effects of having lived with active alcoholism.
I have 3 children. Two teens at home and one 21 year old. I have recommended Alanon to the oldest, and I have taken the teens with me to an open Alanon meeting. At the open meeting, my children met a group of wonderfully caring people and learned that we were not alone. Many people have experienced the same things we did while living with active alcoholism. It helps to know that you are not alone.
You will find lots of support and wisdom on this forum. Pull out your keyboard and make yourself at home. We're glad you are here and we care about you!