Stuck in the Middle, Again

My husband was adopted. It's never been something he wanted to talk about much. That's fine, it's his business. But 13 years ago his biological family found him. It's a long story that I'm not going to get into here, but the gist of it is, his biological mother was only 15 when he was born and since it was the '50s, her family arranged the adaption without her knowledge. By the time she realized she wasn't getting him back, it was too late. She and one of her sisters has respected the fact that he doesn't want a relationship. Her oldest sister doesn't. I have kept in touch with her because she never had any other children, and my children are her only grandchildren, and quite frankly, I like her. But because it is what it is, it is an uncomfortable relationship. A week and a half ago one of her nephews died, the son of the oldest sister. He lived out of state and I figured the funeral was there. But apparently there is going to be a funeral here this Saturday and this sister called and left a message that she expects us to come to the funeral. This is a man we have never met, probably never would have. My husband said "no" outright, which is just as I expected. I have no desire to go. I have a friend who had surgery this week and I had told her I would help her out Saturday. I know this sounds cold hearted. Losing a child, even when that child is in his 50s, has got to be the worst pain there is. And I feel sad for her. But I just can't believe in her grief that she took the time to call and tell /(order) us to come. I'm tied up in knots about this, and just a little mad. I hate being put in these kinds of positions!