Why Sandy Hook Survivor Henry Terifay Has the Name of Slain Classmate Chase Tattooed on His Back (Exclusive)

"I try and remember him in a good way, not in a terrible way where I get sad"

Sandy Hook survivor Henry Terifay still thinks a lot about Chase Kowalski, who was one of his best friends at their elementary school in Newtown, Connecticut — until Chase was killed, along with 19 other students and six educators, in a mass shooting in December 2012. He was 7.

“He was one of my closest friends. We hung out all the time,” Terifay, now an 18-year-old graduating senior, tells PEOPLE in an interview as he and other survivors and new grads reflect on their lives now.

When he turned 17, Terifay says, he got Chase's name tattooed on his right shoulder: The design includes Chase's name in cursive, with a green heart for Sandy Hook remembrance at the end of the "e." (“The [artist] did not even make me pay for it,” Terifay says. “He knew the family, actually.”)

The tattoo is a tribute and a reminder of the toll of gun violence in America, which Terifay, as a member of the Jr. Newtown Action Alliance, has pushed to change.

"I don't want to hear, 'Our prayers are with you,' because unfortunately, your prayers don't really do anything for me," he says. "I just really want things to be different."

For more from surviving students and new grads and the parents of those who were killed, read this week's issue of PEOPLE, on newsstands Friday.

Terifay says he got the tattoo of Chase's name on his shoulder "so that when I wrestle, it could show through my singlet. And in the yearbook, in the wrestling section, you can see a close-up picture of me and you can see his tattoo in it."

He sent that to Chase’s mother, Rebecca, who thanked him. “He wouldn't have been in the yearbook, otherwise,” Terifay says. “She was like, 'I was afraid he wouldn't be in there, but I appreciate you.’ ”

The first-grade classmates he lost in the mass shooting aren't ever far from mind, Terifay says. "I think about them all the time."

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“Every time I get ready, I can see [Chase's] name up on my shoulder,” Terifay says, adding, "I try and remember him in a good way, not in a terrible way where I get sad about it. I try and think about him in a positive way and just keep moving forward and remember him but not be sad about it.”

Nearly 12 years later, he can recall the morning of the shooting and the excitement he felt at planning to make gingerbread houses with his class. "My mom [was] on the way," he says. "A couple parents are already there — and we hear these loud bangs."

He says he then heard the principal, Dawn Hochsprung, go on the loudspeaker system and though he doesn't remember what she said, "you can hear him [the shooter] go in there and shoot her and shoot the rest of the front office. You can hear the phone drop to the floor."

Related: Sandy Hook Survivors, Now 17 and 18, Reflect on Trauma While Growing Up and Their 'Happy-Sad' Graduation (Exclusive)

Terifay's teacher became "so protective and caring" as she led the students to cubbies to shelter in place, where they played games, he says.

One parent who had volunteered in his classroom to make gingerbread houses was an ex-Marine, he says. When the police knocked on the classroom door after the shooting was over, he remembers that father asking the officer to slide his ID under the door for confirmation.

"Then they line us up and they have us cover our eyes and walk out of the building," Terifay says. "I met my mom in the parking lot and I see her fully in tears. I've never seen her like that before and I haven't seen her like that since. I don't really want to see her like that again."

Terifay's best friend now was a student in one of the two classrooms that was attacked, he says. "We've been best friends since then. it really could have been him, too. It's really crazy to think about how all of those people, we're going to graduate without them."

The main message Terifay, who plans to study communications at the University of Hartford, wants spread is that he doesn't want people to feel sorry for what he survived. He wants real, "commonsense" change to lessen the threat of more violence.

Related: Parents Who Lost Kids in Sandy Hook Share 'Bittersweet' Feelings About Survivors' Graduation (Exclusive)

He, like other young activists who have been motivated by living through mass shootings, is calling for more background checks, restrictions on assault-style weapons and more.

"I don't want people to tell me, 'Oh, I'm so sorry. That was terrible and you're so strong,' " he says. "I don't want to hear, 'I'm sorry.' I just want things to be done. We say it all the time, but it doesn't change ever. I'm sure there'll be another school shooting tomorrow or the day after that, which is terrible."

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