Although I don't know much about you, or heck, even know you I've been quite a quiet fan of yours.
Most people do not have or lack paitence so they must act in a way to attempt and rush you, like a three year old would in a candy store, if they don't get what they want they'll throw the biggest fit they have balled inside of them.
And if they throw a fit over a little piece of art that's over-due then they've got another thing coming, some artist have about a 3-4 month waiting list when it comes to art.
Just for a little tip if they continue to act rude and or start to make threats then you should report them to a mod or even admin, it'll fix the problem so nothing else will happen, or just foe them (I think that if you foe someone they will not have the ability to PM you.)