I'm grieving with you. I have been there and understand what it's like to say goodbye to a son in the morning and never see him alive again. I understand the numbness, dealing with the mortuary, waiting to see the shell of your son that is left. Our distraction was sharing a meal with close friends who knew our son well and weren't afraid to talk about him and our memories, even the humorous ones. I'm so sorry you had to go through this, too.
I'm glad you have the GoFundMe. It didn't exist when Jason died in 1991. My mom covered it. It was while I made the arrangements a few years later for my mom (whose estate covered the cost) and three years later for my daughter, whose remains had to be shipped from Texas, that I realized the full cost of those arrangements. I'm glad you will have help. We don't plan financially for final arrangements for our children. And, as you say, one isn't in great shape emotionally while making those arrangements.
A word of caution. I hope you will follow the advice not to make any decisions you don't have to better than I did. I have regretted many of mine I made within a few weeks and months after Jason died.
This was especially true of the distribution of his belongings. I made impulsive emotional decisions. I also started a business to distract me, and I now regret that. There is a good reason they advise you to delay important decisions for a year if you can.
I will keep you in my thoughts and prayers. I can assure you that enough time will ease some of your pain and that even as soon as three years you may be much closer to normal than you are now. Keep writing about your son and talking about him. That helped me. Your true friends will let you.