He feels like he's not a father since we MC😪

Angel • Hoping for a blessing. MC 2.22.16 RB🌈 8.9.18
I'm very sadden by the comment my SO said earlier. His step mother tag him in a post on fb wishing everyone a happy Father's Day. He flat out said I'm not a father, I don't know why she put me in it. I looked at him sideways and said well baby yu are a father the only difference is our baby is in heaven. I had a hard time on Mother's Day but I can only imagine what he's going thru since it was put in Facebook. What's the best way for me to help him get thru this?