My friend smells bad and so I let her know about it.
What made you tell her she smells bad?
I'm annoyed by her reaction, every time I said it she burst into tears. It's annoying.
You should consider thier feelings before you tell them they smell. If you are direct and kind with your friend, there may be no need to tell him or her whether or not others have noticed the smell.
Nah, I'm going to badger her until she dies from crying.
Why would you want to hurt your friend? If you love or care about someone enough to call them a friend then you shouldn't want to ever upset them when you don't have to.