I need a few opinions on a family situation.?

Your sister is going thru a rough time, but that is no excuse to treat her children badly or neglect them. Sometimes when people are going thru this they tend to not listen to people very well, or they are hurting too much to think things can get better. If everyone has tried talking to her, she obviously has made her choice. She will probably come around in time, and hopefully she will not have lost her children by that time. Child Protective Services takes a dim view of this kind of treatment of children. Your sister is the adult, she needs to buck up and take responsibility.