((((((((((HUGS))))))))))
I am soooo sorry that you are sick!! I hope and pray that this is treated fast and easily (relatively) and then you can go on enjoying your life. You will know when to tell him. Follow you heart and instincts. Just please make sure that he does not hear it from gfgmom or anyone else.
I will offer this just to give you a perspective that might not have occurred to you.
My parents, esp my dad, spent quite few years making sure gfgbro was the LAST to hear of things. Quite often they would wait until there was NO way for difficult child to get to a funeral or whatever before telling gfgbro. Much of this was because gfgbro spent much of the year working in national forests and other remote areas and they didn't want him to feel bad for not being able to get to the funeral, wedding, hospital, whatever. Gfgbro spent those years being SURE that no one trusted him to behave appropriately (very true in many instances, but not usually funerals, weddings, etc....) and that my parents were trying to hide him.
Gfgbro always felt a strong bond with our great gma. He was the only one of the great grands to ask to spend the night at her home, and the only one she allowed to do that. He did NOT behave well in her town, but was able to hide that from my folks and the neighbors never told GreatGma. When GreatGma died, bro was clearing trails in a national forest. My parents decided not to tell him until AFTER the funeral. I was only 19 but I told them it was wrong and mean. I was ordered to not tell him. Not hard because he didn't have a phone. But I found the number for some friends of his and told him anyway. My dad FREAKED completely. I finally screamed at him that if he hated gfgbro that much then he needed to just stay away from him but to keep doing this was cruel and made difficult child KNOW that he was hated and that they didn't think he could make an adult decision even though he had never acted out when the family was at a funeral or other major family event. I don't think I have ever, before or since, screamed at my Dad.
Dad was totally and completely shocked. Not so much by my yelling, though that did get through to him that I was beyond just upset. He had NO idea that gfgbro thought my dad not only didn't love him but also didn't want him ANYWHERE around the rest of the family because he couldn't be trusted to behave. Now in many instances gfgbro truly couldn't be trusted, not to behave or to do/not do many other things. BUT we had always pulled together in a crisis, and Dad had NO clue that this was how difficult child thought and felt.
My dad was trying to PROTECT my brother from blowing his entire summer's pay to get to a funeral that my GreatGma never wanted anyone to have and would NEVER have wanted any ofu s to spend $2 to get to, much less hundreds of $$.
Dad and bro finally talked it out and worked through it, and they saw that they were each trying to help and protect the other. But even after YEARS of never knowing until it was too late to get there, it took something dramatic to get my dad to really SEE how keeping things from bro was hurting bro and all of us.
DDD, Please don't let someone else tell difficult child. It will end up making difficult child ffeel that you don't trust him to support you when you are in a crisis. This may be true, but it still hurts enormously to thing your family is having that reaction.
You need your family to help you through this. Don't cut yourself off from that.