@Superlyte27 I so sorry for your loss. I have never lost a child of my own, but I feel that I can empathize with your grief.
In October 2017, I went on the Aquacat in the Bahamas. Less than an hour after walking in the door when I got home, the phone rang. It was my brother. He told me "You'd better sit down. While you were gone, Mimi (his daughter Michelle and my God daughter) took a sudden turn for the worse (She was 39 and a mother of 3 who had been fighting cancer for 4 years). The doctors give her anywhere from a few days to a few weeks." Well, the doctor found some meds that were better and soon Michelle was released from the hospital. A year ago this week, she told her husband that it was time, and she left her home for the last time and was admitted to a nearby hospice for end of life care. On 17 Feb, the phone rang at 6:30am. It was my brother. He simply said "It's over." Mimi was not only my God Daughter, she was also the closest thing I ever had to a child of my own. I know that my brother felt responsible for her death. Our mom died of breast cancer at 42, and my brother felt that he condemned his own daughter to an early death when she was diagnosed.
A few months later, in May, ironically on my brother's 66th birthday, he collapsed while walking the dog. He was admitted to the hospital and initial indications were to gather the family. He appeared to be getting better but he needed blood transfusions every few days and nobody could figure out why. They kept running tests, but couldn't come up with anything definitive. On 24 May, which would have been Michelle's 40th birthday, the word "Cancer" was first mentioned as a possibility. He was scheduled for a consultation at a local Cancer Clinic and while at the consultation, he took a sudden and dramatic turn for the worse. He was immediately admitted for end of life care, and he died on 1 June.
So although I have never lost a child of my own, I lost my entire family in the space of 5 months to cancer.
Here is my advice. Find a professional to help you deal with your grief. Friends and family may have the best of intentions, but they are all too close to the situation and they don't have the type of training that this needs. Find someone like a Social Worker, or other mental health professional whose only interest is helping you develop the tools that you will need to deal with something that no father should ever have to deal with.
I wish I could tell you that everything will be OK, but the reality is that things have changed forever. I sincerely hope that you find a way to deal with the world as it now is. Make no mistake, it will be a hard journey, but it is one that can be made. You mentioned your son's sense of humour. It's OK to laugh at the things that you know he would have found funny. Laughter has amazing healing powers.