I'm going to let a friend smoke with me
Is smoking something that your friend wants to do?
He's a sick man and we go to the same hospital. Letting him smoke with me would make him feel good.
It's kind of you to want your friend to feel better.  Sharing with a friend is a great gesture and a way to show you care.
I know but it's cheating, he needs to learn to cope with my cancer. I need to stop being so nice.
It is great that you are trying to help your friend feel good. Smoking weed is something that is actually pretty beneficial for those who may have mental health issues or physical issues. Hopefully smoking will give your friend a little bit of relief.