Boyfriend’s brother

My boyfriend had a best friend and they were inseparable. As far as anyone knew, they were brothers. He loved him with all his heart and they always had each other’s backs. His best friend had three sons and my boyfriend watched them all grow up, the oldest being 15. Last night he lost his best friend, on Christmas nonetheless. They knew each other for almost 2 decades. He’s mourning his brother, his best friend, his confidant. I didn’t know him as well as I’d like but I’m mourning the father his sons lost. The son his mother lost. The brother his siblings lost. The best friend my boyfriend lost. He had been in the hospital for almost 3 weeks with a multitude of problems and despite it not being sudden, it felt sudden. I kept telling myself “He’ll pull through, it’s not his time, those boys need him.” I’m mourning what could’ve been. He’ll never see his boys grow up. He’ll never see them marry. He’ll never see his grandchildren. My boyfriend was his best man at his wedding and he’ll never be his at ours. He won’t be here when we have our child. Won’t be the godfather like I already hoped. I won’t be able to get to know him like my boyfriend knows him. My heart hurts for his boys, his family, my boyfriend and myself.

He was only 38.....

I need advice. How do I handle this? Not for my sake, but for his boys, family and more importantly my boyfriend. What should I do? What do I say?