First of all, it tells the terrible depravity into which Israel had fallen in this era. They were a bunch of godless reprobates. Even their religious leaders were depraved. No man or woman was safe from harm. The message of Judges is, "Look what happens when people fall away from God."

As far as the cutting her into pieces and drop-shipping them to the 12 tribes, it was an ironic parabolic action of calling Israel to account for her sins. The Levite was hoping to convene a general assembly (compare and contrast with 1 Samuel 11.7, where oxen were cut up and sent to call Israel to muster an army). The Levite was showing Israel the depth of depravity, especially of Benjamin (the tribe of their future King Saul). The crime was put on display to the whole nation by this symbolic act, which it seemed to have accomplished (Judges 19.30).

You'll notice, then, that Israel gathered to fight against their own tribe, the Benjamites, in Judges 20.

The whole story is a sordid tale of a country gone wrong.

What is the point of the disgusting story in Judges 19 verses 22-30?

So basically a guy stops at a town, the men there want to rape him, but he gives them his concubine instead. They proceed to gang rape her to death, and then he cuts up her body and sends peices of it to different parts of the land. Why is this in the Bible? Why should we read about this? What's the point?