Billy Ray's divorce case just settled and is signed, sealed and delivered in the Tennessee court system ... lawyers from both sides confirmed to TMZ.

The terms of the divorce settlement, obtained by TMZ, call for Firerose to exit the marriage with $0 ... though Billy Ray is handing over his claims to credits and royalties for songs the former couple wrote and published together.

Billy Ray's lawyers, Rose Palermo and Jason Talley, tell TMZ … BRC and Firerose reached a settlement agreement at mediation Friday, and on Monday morning the court declared them divorced.

We're told Firerose recently changed her last name from Hodges to Cyrus ... and Billy feels the change validates his assertion that her sole reason for marrying him was to obtain his last name.

In a statement through his lawyers, Billy tells TMZ ... "This has been absolutely the most crazy insane scam I have ever heard of. Let alone the fact I'm right in the center and basically the target of the scheme. It's unfortunate it played out this way. Not only was it a web of lies that put me in physical danger, it was a matter of the heart. Love is blind, that's for sure."

TMZ broke the story ... Billy Ray filed for annulment back in May, only 7 months after he tied the knot with the Australian singer.

BRC claimed Firerose misled him about who she really was and was trying to use his last name to bolster her music career ... and she claimed he left her after she realized she required a preventative double mastectomy.

Now, less than 3 months later ... it's all over.

A source close to Firerose familiar with the litigation tells TMZ … "If this went to trial, Firerose and her team would have provided a significant amount of evidence to prove he fabricated a narrative that would benefit his public image.

"There is no doubt she would have been awarded the divorce, but it was much more important to her that this continuous smear campaign end, and the emotional turmoil stop so she can close the door on this chapter and recover from her surgery peacefully."

While the divorce only took a few months, there was plenty of drama and mud slinging ... including the release of an audio recording featuring Billy Ray laying into Firerose and calling her a "f****** bitch," plus a "dumbass" and an "idiot."

Remember ... Billy Ray and Firerose fought over access to his credit cards ... and there were abuse allegations as well.