Hi, I know you already made your decision, but I will swear I work for your boss's twin. I had major problems with my boss when I had twins and then over back surgery I had 2 years ago. He was in the Navy for years, attended the Navy academy and is super fit. I didn't want to tell him what I was going to do, then a co-worker suggested that I do tell him because he is such a health nut. I did decide to tell him and he was way more supportive than I ever dreamed of. So you never know, he could surprise you. I would probably keep quiet until the last minute, then let him know. Good luck with whatever you decide.
Julie