Should I tell my boyfriend I'm dying ?

I have been sick for a long time now. I'm okay with dying a bit earlier (like at 30). I'm 23 currently and got diagnosed with an endocrin disease at 10, also right now I'm on iodine supplements because I don't have a thyroid. My weight is fairy well but the doctors told me that my kidneys as well as other things arnt doing well due to the treatments I faced as a child. I get sick often, the flu will cause me to pass out and go to the hospital and I have an severe iron deficiency. My boyfriend, Christopher doesn't know about this. We have been dating for 3 years and he knows I have a "thyroid problem" so that's why I go for tests, take Lots of medication and get so sick. I found out about my vital organs starting to decrease in percentage. The doctor said with extreme health precautions I'd only loose roughly 3% a year. Right now I'm chilling at the hospital typing this while my boyfriend is at my feet. They are just checking for diabetes and doing a blood test. Should I tell my boyfriend I won't live a long time? He's really old school and said he won't re marry or anything but I want him to. I want him to move on and love someone else, I look healthy but my doctor said to tell friends and family but how ? Any ideas ? 
Thank you for reading this long post