Nick, 39, revealed the news on Twitter on Tuesday, writing, “After careful consideration, my sister Angel and I regret that we were required to seek a restraining order against our brother Aaron today.”
Nick said he and his sister made the decision due to 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 wrote.
The star shared that he still loves Aaron, 31, and hopes “he gets the proper treatment he needs before any harm comes to himself or anyone else.”
Nick added the hashtags #mentalhealth, #guncontrolnow and #guncontrol.
A representative for Nick did not immediately respond to PEOPLE’s request for comment.
Aaron reacted to the restraining order on Twitter, also on Monday, sharing, “So my brother just got a restraining order against me.”
“And I was just served lol.”
“Take care. @NickCarter we’re done for life,” Aaron continued. “I haven’t seen him in four years. And I don’t intend to.”
Aaron also responded to Nick’s accusations that he wants to harm his family.
“I am astounded at the accusations being made against me and I do not wish harm to anyone, especially my family.”
“All I ask is for my family to leave me alone. This is blood. Not love. I will never be around you and I don’t want to be around you. I am the one who said I’m done then you send me this?! Ok. Stop trying to be 5150’d before I file a harassment suit myself nick I have the $,” Aaron continued.
“Don’t come crying to me after I block you either,” Aaron wrote to his brother. “I’ll never unblock these backstreet boy fans for attacking me. I’ll never unblock these backstreet boy fans for attacking me. When I knew what my ‘family’ has been doing all along when I’m at home minding my own f—— business.”
News of the restraining order comes after Aaron opened up about his history of addiction and drug use on Friday’s episode of The Doctors.
On the segment, Aaron found out the results of his drug test, after having previously revealed the long list of prescription medications he’s on for his mental health.
Delivering the results, host Dr. Travis Stork told Aaron that his “urine tested positive for marijuana, extended opiates, hydrocodone as an example, and benzodiazepine,” the last of which could be explained by one of the medications the singer had been prescribed to treat his multiple personality disorder, schizophrenia and acute anxiety.
Although Aaron was initially at a loss for how he could have tested positive for opiates, maintaining that he hadn’t used the drug since 2017, he remembered that he had been prescribed hydrocodone when he recently “got his teeth done.”
Aaron went on to clarify that while he was taking the opiate, he did not mix it with his regular medications and that he threw the remaining pills away after taking two because he didn’t “want to be on them.”
Aaron, who claimed that he was going to quit smoking weed “because it affects my medications,” also opened up about his huffing addiction for the first time.
“It’s something that I’ve kept secret from the whole world until now,” he said, explaining he has to take gabapentin and fish oil “to repair the serotonin receptors in my brain.”
The singer explained that his sister Leslie, who died from an overdose in 2012, was the one who introduced him to huffing.
“Started when I was about 16,” he said, noting that he “didn’t really touch it until I was about 23, right after I did Dancing with the Stars. And I started going to Staples and Office Depot, and different places, buying it with cash so it wouldn’t be reported on receipts or anything like that, so no one could trace me.”
“That’s my truth,” he said, adding that these days he’s “doing amazing.”