A Bronx cop who had just gotten engaged fatally shot himself in the head at home Tuesday morning — the eighth NYPD officer to die by suicide this year, authorities said.

The tragic statistic is already double the number of suicides that occurred in the department on average annually in the past few years, authorities said.

“How many people are going to end up dead before something changes?” said Ed Mullins, president of the Sergeants Benevolent Association.

“I think they need to look at the big picture,’’ Mullins said of NYPD brass. “I think they need to take a look at PTSD. I think we need to look into the idea of annual therapy, basically extracting the trauma that builds up.’’

The latest cop to take his own life, 35-year-old Officer Johnny Rios, was a seven-year department veteran temporarily assigned to a detail around Yankee Stadium, officials said.

He was off-duty when he shot himself at about 3 a.m. in the Yonkers home he shared with his fiancée and her children, law enforcement sources said.

She was home at the time, sources said, although it’s unclear if her kids — whom a neighbor said were a 17-year-old boy and an 8- or 9-year-old girl — were there.

“They’re a very happy couple,’’ said the neighbor, who asked that her name not be published. “They never had domestic issues.

“They were planning on getting married soon. [Rios] was excited about it . . . He showed us the ring before he proposed. That was about three weeks ago.

“I’ve never seen anything in him that made me think he could do this,’’ the neighbor added.

Rios left behind a note, sources said.

Mayor Bill de Blasio in a tweet called the death “heartbreaking.”

NYPD Chief of Department Terence Monahan, addressing the issue on WNYC radio Tuesday, said the department is expected to start hiring more peer-level counselors, “someone [officers] can get to know before you are in crisis.

“We look at this like there is a contagion,’’ Monahan said. “We had averaged four to five suicides over the last few years. Currently this year, we have eight suicides. That is a very large number.”

Monahan urged officers to contact the NYPD’s Employee Assistance Unit if they are “in a dark moment.

“There are stressors of the job complicated by stressors that you have in your personal life and compounded by the fact that you have a firearm on your hip,’’ he said. “We will help you find the right therapist and make the right accommodations.’’

The number for the National Suicide Prevention Lifeline is (800) 273-8255.

Additional reporting by Craig McCarthy and Larry Celona