Through it all, through all the heartache and loneliness, separated by distance and prison walls, two brothers refused to let go of their lifelong bond.

Rontez Miles and Vondre Griffin had shared an NFL dream since they were 9 years old. In 2013, Miles made the Jets as an undrafted free agent and embarked on a pro career as a reserve safety and special teams demon.

In October of that year, Griffin became inmate LG5242 at the State Correctional Institute in Mercer, Pa., after he fatally shot a man. He claimed he acted in self-defense but later agreed to plead guilty to voluntary manslaughter.

Griffin was incarcerated for more than six years, from when he was first admitted to Allegheny County Jail in the aftermath of the shooting in August 2012 until he was released last September and reunited with his brother.

“It crushes you, man, because everybody in life has somebody they trust, that’s like their right-hand man or their best man, and that was him for me,” Miles told The Post this week at Jets camp. “I felt kinda empty sometimes.”

When the Jets open the regular season against the Bills on Sept. 8, Griffin will be at MetLife Stadium cheering for his brother, watching him in person at an NFL game for the first time. He can’t wait.

“I think maybe seeing him come out the tunnel or seeing him run on the field or maybe coming off the field after a tackle, it’ll hit me,” Griffin told The Post in an exclusive first interview about his imprisonment.

Miles is 39 days older than Griffin. The brothers, who have the same father, come from broken homes in hardscrabble Braddock, Pa., on the eastern outskirts of Pittsburgh. Miles’ mother is recovering from an addiction to crack cocaine. They spent weekends together even before Miles moved in with Griffin when they were 14.

“There was no backup plan,” Griffin said of making it in football.

“We used to go outside at night after we played the video game all day. … We would go out and run 40-yard dashes and sprints and cover each other and throw the football around. We did that almost every night, run hills.”

They were standouts at Woodland Hills High School. Griffin was the quarterback. One of his pass-catching targets, for a brief time, was Rob Gronkowski.

The brothers signed on to play at Kent State and Griffin was declared ineligible because of financial and legal issues. Kent State wanted Miles to stay, but he rejected the pleas.

“I told him that it was the best thing for him to stay because he was already invested, but he made that decision based on dreams and goals that we had to play together and to stay together,” Griffin said. “That was a very admirable thing for him because he didn’t have to take that sacrifice but he did.”

Instead, they planned to enroll together at Division II California University of Pennsylvania. But Griffin owed Kent State close to $20,000 because he had not been on full scholarship, and he could not obtain his transcripts to transfer. In the meantime, they took courses together at the Community College of Allegheny County and worked at American Freight. Griffin wound up playing two seasons at Thaddeus Stevens, a junior college in Lancaster, Pa.; Miles eventually settled in at Cal U.

In the early morning of Aug. 5, 2012, Griffin was arrested on charges of criminal homicide and carrying a firearm without a license after he fatally shot 37-year-old Tameko Wall in the head outside the Sportsman’s Club in McKeesport, Pa.

According to Griffin, he was trying to break up a fight involving an acquaintance and pulled out his gun with the intention of restoring peace. He said he had purchased the gun for protection after seeing his cousin murdered in a drive-by shooting four months earlier.

“One of the guys that I came with had gotten jumped on by a group of guys because he was talking to a girl that he didn’t know was one of their girlfriends, and they kept beating him up,” Griffin said. “I broke the fight up like two or three times, and out of impulse I just pulled my firearm and just defuse the situation. But the other guys, when they saw me pull my firearm out, they pulled one out, they fired a shot, we took off running, I fired a shot back, the other guy ended up being hit. I was apprehended on the scene and from that moment on I was incarcerated.”

According to a 2012 report in the Pittsburgh Post-Gazette, police said Griffin told them he fired his gun because he believed another man was armed, but said he never actually saw a gun on that man. Griffin remains adamant his actions were in self-defense and expressed remorse for the incident.

“I knew in my heart that what I did was defend myself,” Griffin said.

His brother says the same.

“He’s always been a good guy,” Miles said. “Sometimes life puts you in corners where you have to make decisions, tough ones. Anybody in his situation would’ve did what he done.”

Griffin agreed to a plea deal that resulted in a maximum 10-year sentence. He was 23 years old.

The brothers spoke several times a week when telephone privileges allowed. Griffin followed with pride as Miles carved out a role with the Jets. He cried tears of joy when he read the press clippings. And he was watching when Miles recorded his lone career interception, against Eli Manning at the Giants on Dec. 6, 2015.

“All of ’em were in their cells, but they could see the TV through their cells: ‘We see your brother, we see your brother,’” Miles said.

Griffin reassured Miles through the ups and downs of his NFL career.

“I was always assuring him, like it comes with the territory of you accomplishing your goals, accomplishing your dreams,” Griffin said. “Always reminding him that he had good problems to have: ‘Just imagine if you were in my shoes.’”

Sometimes he’d remind me when he was in hell or the worst place he could be at, and I’m playing pro football. He would calm me down. - Rontez Miles on his brother Vondre Griffin

Said Miles: “Sometimes he’d remind me when he was in hell or the worst place he could be at, and I’m playing pro football. He would calm me down.”

Because of his NFL career, Miles’ visits were all too infrequent.

“It was hard seeing him in there, don’t get me wrong, but his spirit, his personality, made you feel like we weren’t even there,” Miles said.

Griffin recalls the low point.

“Somewhere in the beginning before I got like a deeper spiritual connection and really trusted God completely with my life, just realizing that I may never see my family on the other side of a prison gate or a prison wall,” Griffin said.

“You get a tray at 3:30 with a piece of bread, some beans and a soup on it, and you may get in bed until the sun comes back up. Guards making you strip and talking bad to you. It’s just traumatizing to lock somebody in this little room every day. They treat you like an animal. You have to remember not to turn into an animal.”

Miles kept encouraging him to keep hope alive.

“When you come home, everything that we wanted to have is here waiting for me. That was his assurance to me,” Griffin said.

On Sept. 18, 2018, Griffin was paroled.

“Tez was outside waiting to pick me up,” Griffin said. “It was a happy day for me, a happy day for my family. It was a lot of laughs and hugs. He was going through his phone, showing me stuff that I didn’t get a chance to see.”

The tears arrived later.

“It was weird, awkward, emotional,” Miles said. “A lot of stuff was different, I grew up a lot in five years. His mind changed a lot for being locked up for that long.”

The first 30 days after his release were easy, Griffin said, a “joyous celebration” as he was surrounded by loved ones. But reentering society is a daunting transition.

“Once you get out of there, you hate that place so much, you want to forget that place, you want to forget the trauma that it puts on you,” Griffin said. “I’m 29 years old when I got out of prison. Prison makes you a little bit colder, it makes you a little bit more defensive, a little bit more aggressive and angry because surviving in that kind of environment, just to get treated like that by guards and other inmates and stuff like that, it does something to a human being that’s inhumane. … You have to kinda unlearn some of the negativity that you experienced and then you have to embrace and trust the new experiences that you’re about to take on.”

Griffin got a job paying $10 an hour to unload trucks at a recycling center in Braddock, but said the soot aggravated his asthma and sent him to the hospital. Now Griffin reports he is working at a fine-dining restaurant in Braddock and taking real estate classes. He said he would like to give back to the community by working to launch a reentry program with a real estate focus or by starting a trade school for younger adults.

“I can’t be bitter,” Griffin said. “That’s one thing I learned about life and emotions, like I can’t be stuck, I can’t be mad, and I do share some responsibility in that equation. It still was against the law for me to have the firearm and for me to get caught with the firearm and then somebody lost their life in the process and me doing something that I wasn’t supposed to do. … There’s no room really for me to be bitter, and I also know that who I am in my heart has a lot to do with me doing something about it anyway. It gives my life more substance.”

Miles plans to get his brother to as many Jets games as possible this year.

“We’re going to be involved in a lot of positivity, man, and I’m just happy he’s back,” Miles said.

For Griffin, an old dream dies. A new dream grows.

“My life purpose,” Griffin said, “is to fill that void between somebody becoming a Rontez Miles or becoming a Vondre Griffin.”