An upstate man allegedly slit the throat of a teenage social media influencer he was dating — then posted a grisly photo of her lifeless body to Instagram along with a message that said “sorry,” according to police and reports Monday.

Brandon Andrew Clark, 21, of Cicero allegedly posted the gut-wrenching image of Bianca Devins, 17, on Instagram early Sunday — after the pair had attended a concert in Queens — before bizarrely calling the cops on himself, Lt. Bryan Coromato said.

When cops found him lying next to his black SUV in Utica, he allegedly pulled a knife and slit his own throat, then posted a photo of his neck gushing blood on Instagram, the police officer said.

Afterward, he took a cellphone photo of himself lying across Devins’ dead body — which cops found under a green tarp near his SUV, police said.

Clark was rushed to St. Elizabeth’s Hospital, where he underwent surgery, police said.

He later was charged with second-degree murder in the death of Devins — who has about 6,000 followers on Instagram and was reportedly popular as an “egirl” on the Tik Tok app, according to police and reports.

The pair, who met on a dating app, had been in a relationship for roughly two months when they went to a concert in Queens on Saturday night, according to Coromato.

They got into an argument at the show and drove to Utica, where police believe Clark allegedly pulled onto a side street and killed her, Coromato said.

Police first began getting calls from Clark’s concerned social media followers around 7:20 a.m., police said. Instagram deactivated his account Monday morning, a spokeswoman for the company said.

The bio for his Instagram account read “10/06/1997 – 7/14/19. Just know that I feel no pain now,” according to the news site.

Devins’ heartbroken family mourned her tragic death.

“Bianca, age 17, was a talented artist, a loving sister, daughter, and cousin, and a wonderful young girl taken from us all too soon,” her family said in a statement. “Bianca’s smile brightened our lives. She will always be remembered as our Princess.”

On Instagram, Devins’ sister, Olivia Devins, called Clark a “family friend.”

“It wasn’t just an ‘internet boyfriend’ this was a close family friend whom we’ve met and trusted so much. I do not want false information being spread around,” she wrote.

She also posted a heartfelt tribute to her sister, who graduated from T.R. Proctor High School last month.

“I hate that I have to write this. I hate knowing you’re not going to ever come back home. You were the best sister anyone could’ve ever asked for. Thank you for always being there for me. Thank you for being the best sister I could ever imagine. Thank you for always protecting me and sticking up for me. I am going to do this for you. Every day I’m going to do my best and I’m going to get through this thing called life and do it all for you. Rest easy, I love you so much forever and always,” she wrote.

– Additional reporting by Zachary Kussin