Let me tell you, it is absolutely not ok. The family does notice who is and isn't at the funeral and they WILL assume you are just not emotionally involved. I have seen this scenario play out. Don't be surprised if people stop showing up at something you organize. Breaking down at a funeral is absolutely ok and will strengthen the bond with those left behind.
I made the complete opposite experience thankfully. I am very open about this and my friends understand. I dont care about their families, I care about the person in the casket.