I'm going to break up with my girlfriend over text while she is abroad visiting her dying grandfather
Why do you want to break up with her?
I want to experience being single again.
Breaking up with someone when their family member is dying seems a little harsh, especially over text message. If you really care about your partner it may be a good idea to at least wait until she gets back so you can do it face to face. If you simply want to be single again then it seems you dont have a lot of interest in your girlfriend anyway.
I'm going to do it because I'm bored of her and the moment she leaves I'm going to go have fun.
Breaking up with her via text while she's dealing with a death is cruel and disrespectful. You can wait until she gets home to move one as whether you want to be her partner or not, you should be kind to her. You wouldn't like her to do that to you.