My Grandma died on my boyfriend's birthday

My grandma got hospice yesterday and we visited her. She wasn't doing well but she was still talking a little sometimes. Today, we got a call just before we were gonna drive there that she passed away. We've all been grieving for her. I miss her so much already, I just wish I got to spend more time with her and be there with her in her last breaths, but two of my sisters were and I'm grateful she wasn't alone. It's my boyfriend's birthday today though, and he already knew that she was nearing her death. I was planning on not telling him that she passed until after his birthday, but is that the right thing to do? He's busy right now and will be for a few more hours and has no idea. I just don't want to ruin his birthday, his sweet sixteen. What do I do?