I'm going to break up with my girlfriend a week after her grandfather died
If it is the right time for you then you need to think of yourself first, but why are you breaking up? I'm just curious.
I'm annoyed at her crying all the time.
Crying is a natural response especially if she was close to her Uncle. Give her some space and time and then maybe get back together again, but right now she needs your support, just as you would if something like that happened to you. It's okay to break up but you might regret it later for this reason.
Why the fuck would you care. Stop trying to make me feel bad for the shit you think is right.
I'm just trying to be honest. You can still break up with her. I'm trying to just make you aware that some people have more feelings than others and if you break up now she might not want to take you back again for ditching her at this sad time in her life. So it is up to you either way.