Sonny was screaming at Nina at the grave site about her being responsible for his poor family grieving for him there. But, didn't they already do the funeral/headstone blah blah junk BEFORE Nina went to Nixon Falls and found "Mike " and kept the secret. I remember something about Nina showing up at the cemetery and everyone being outraged that she dared do it during Carly's tragic loss, blah blah. So yes, Nina prolonged everyone's grief by not coming clean when she found out Sonny was alive. But they had already done the funeral, headstone etc. She was not responsible for that taking place.