Question on etiquette:

My X BIL died last night. He and my sister were married for 20 yrs and had 3 great kids. I baby sit for their grand-daughter (my niece's daughter) a couple of times a week. When the divorced it was harsh, he and his FOO hate my sis and her family (me). My nephews and niece remained close to their dad. At my nephew's wedding he refused to speak to me. SO>.... I obviously care a great deal about my nephews and niece. What is right? Should I just send flowers/sympathy card, offer to take the little kid(s) and tell them call me if they need me? Or should I go to the final events and possibly make his new wife, sister and mother uncomfortable?