TRIGGER warning, still born dates no pics

Michelle 🇬🇧
I'm asking for advice as I dont know how to cope. Long story I'll try and shorten it. Last March on the 8th my Fil's birthday we had a family meal planned that evening. I was 25wks pregnant. I was sent for a scan as his heartbeat wasn't found on the Doppler, I was told not to worry. So I went to the scan alone. I lay down and she put the scanner on my belly and it was silent. She moved it around a bit and then looked at me, put her hand on my shoulder and said I'm so sorry michelle, but your baby has died. I had no idea that had happened and it hit me like a train and I went hysterical. I called my SO sobbing and I was taken to a small side room to wait for him and had bloods drawn and a bereavement midwife come look after me. I just sat there in complete shock with huge tears just pouring out as she spoke to me and I wasn't hearing a word she was saying, I was just completely broken. To shorten the story we didn't go on his dads meal that night obviously and the next day on the 9th, I gave birth to my still born son who to make it worse had died a few weeks earlier and was in a bad condition. I couldn't even kiss him goodbye as he was sticky. 😢 I'm due another son on the 14th of March and it's tainted with pain to think I'll be holding a live healthy boy only 5 days after my son was born dead the year before. The following is my dilemma and reason for this post. My sil text my so yesterday and asked if we're going to there dads birthday meal on the 8th. He tentatively asked me and I had major flashbacks of last yr on that day and started crying. I said NO how can I go out celebrating on the first anniversary of our babies death 😭 he said I'll ask them to do it the Sunday before. I feel guilty to make him change his birthday celebrations to a day which isn't his birthday. But I am dreading the 8th/9th so much being the first anniversary. I know I'll be in bereavement mode those 2 days and crying a lot. Am I wrong to make him change it? I can't do that every year and I won't as time passes, but it hurts my heart so badly thinking about that day. Should I try and suck it up or go ahead and let them do it on Sunday not his birthday?