Nick Carter says he and his sister Angel have obtained a restraining order against brother Aaron Carter.

“In light of Aaron’s increasingly alarming behavior and his recent confession that he harbors thoughts and intentions of killing my pregnant wife and unborn child, we were left with no choice but to take every measure possible to protect ourselves and our family,” Nick Carter, of the band Backstreet Boys, said Tuesday night on Twitter, adding hashtags about mental health and gun control to his tweet.

Aaron, who has been singing since he was a child, fired back at his older brother for hours on Twitter, saying in part that he was cutting ties with Nick. Aaron also aired a lot of dirty laundry about his family and accused his brother of raping a woman. (Nick, 39, faced a 2003 rape accusation last year but denied it; prosecutors tossed out the case, citing the statute of limitations.)

During the barrage, Aaron said Nick was paying him back for supporting the woman who had accused the Backstreet Boy of rape. “[T]o retaliate you call the police to take away my legal guns and you file a restraining order,” he tweeted.

Aaron, 31, told TMZ on Monday that he’d been visited by law enforcement on Sunday night and questioned about his mental health. Police left without placing him under a psychiatric hold, the singer said, after he convinced them he was not a danger to himself or others.

“There was four deputies that came … and then a mental evaluator with a clipboard ready to take me and put me in a straitjacket,” Aaron told the website, adding that he advised police that he had loaded guns around the house, but none on his person.

The singer inherited hundreds of guns after his father died in 2017 and recently said on Instagram that he had legally purchased a pistol and two rifles.

His mental health has been discussed a lot lately in part because of recent appearances on the TV show “The Doctors.” Though any diagnosis has been unclear, he went on the show last week and revealed he had been prescribed Xanax, Seroquel, gabapentin and trazodone. He also revealed that he went into rehab in 2017 because he was huffing.

“I was in a really terrible place. I was abusing medications. I was in a toxic relationship. I was in complete denial. I was so into the addiction, I was just like, ‘I’m just going to let myself die,’” Aaron told “The Doctors.”

“I still struggle, but … I’m creative. I’m starting to get acclimated to my medications. I gained 45 pounds. I manage my career, I negotiate my contracts. That’s what it’s like for me being sober.”