Guys, everyone, stop, this is an April Fools. @peculiarbanana already debunked it here. Here is the link to the original article.
More details on why this is not true:
First and most obviously, the original article was tagged “satire” and posted on April 1st. This was cropped out of the screenshot, which, as @peculiarbanana says, is dishonest.
That’s not a letter, it’s an official cylinder. A bit of Googling identified it as “the restoration of Sin’s ziggurat at Ur”. Mesopotamian letters were usually rectangular and placed in a clay envelope, like this (source):
Nisaba is not a male name, it’s the name of a Goddess. A mortal would never have been simply called Nisaba - especially not a Neo-Babylonian man, since Nisaba is a Sumerian deity. Her Babylonian equivalent is Nabû, who would’ve been much more likely to appear in a male name of the time (Nabonidus himself is an Anglicization of Nabû-naʾid, “Nabû is praised”).
I’m fairly sure that a royal concubine who cheated on the king wouldn’t have been let off the hook with a sad “pick up your stuff and go away”. Her fate would have been significantly more gruesome.
Liberty University, which is credited with the discovery, is a private, conservative Christian university which promotes creationism. They are not currently excavating in southern Iraq. I would know - I personally know the teams which are excavating there, and none of them are creationists.
Are you disappointed that there aren’t any Mesopotamian breakup letters? Are you going back to thinking that the Mesopotamians were boring after all (except for the infamous Ea-Naṣir, of course)? You needn’t be! I previously wrote a post with actual quotes from Anatolian letters, all of which are 100% real and 0% boring. They may not contain any breakups, but they do feature a chariot crash, a brother left on “read”, and a very sassy king - which are just about as fun as a fake breakup letter, don’t you think?