"Jessie and I set up [a Christmas tree] and never got a chance to decorate. I didn't have the heart to take it down," dad Neil Heslin says

Jesse Lewis always looked forward to the holidays, his dad says, no matter the occasion.

“Easter or Fourth of July, Halloween, Thanksgiving, he just loved the holidays, one as much as the other,” says Neil Heslin of his son. “But what makes this holiday season, Christmas, Thanksgiving to the New Year, harder is that’s when the tragedy occurred.”

It has been five years since Jesse, 6, was slaughtered with 25 others — including 19 other children — in a gunman’s rampage at Sandy Hook Elementary School on Dec. 14, 2012.

The time since the massacre has been an odd thing for Heslin, at once feeling so short (“some of it seems like it was just happened yesterday”) and “so long.”

“It’s been a journey. So much has happened, so much has changed in a five-year period, in my life anyway,” Heslin tells PEOPLE. “And I’ve experienced so much.”

One thing that hasn’t changed is Jesse’s death.

“The pain and suffering doesn’t get any better, doesn’t go away, doesn’t get any easier as time goes on,” Heslin says. “I guess it gets more distant and it’s not as raw, but it’s always an open wound. There’s always reminders of the loss.”

• Watch the full episode of People Features: Remembering Sandy Hook Elementary — 5 Years Later, streaming now on PeopleTV. Go to People.com/peopletv, or download the app on your favorite streaming device.

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Jesse Lewis
| Credit: courtesy Scarlett Lewis

Dec. 14 is particularly painful: Heslin lost his son on that day in 2012 and, five years earlier, lost his mother on the same day. “It’s like a day you just don’t even feel like getting out of bed or you’re afraid to get out of bed, statistically it being a tragic day,” he says.

While he tries “go through the motions for the holidays,” one thing Heslin will not be doing this year is putting up a Christmas tree. It’s only this year that he took down his last one — the same tree that Jesse helped him set up before the mass shooting.

“I had one up for five years that Jessie and I — four years — Jessie and I set up and never got a chance to decorate. I didn’t have the heart to take it down,” Heslin says. “I didn’t have the heart to look at it, quite frankly. This past year I took it

“I’m not putting another Christmas tree up. I just don’t have it in me.”

Jesse’s loving personality inspired his mom, Scarlett Lewis, to launch the Jesse Lewis Choose Love Movement to help kids with social and emotional learning. Her older son, J.T. Lewis, Jesse’s brother, was honored last year at the Teen Choice Awards for founding Newtown Helps Rwanda.

“It’s been five years, unbelievably, since the tragedy … and not a day goes by, not even a minute, where J.T. and I don’t think about Jesse, and miss him,” Scarlett tells PEOPLE. “And of course, I spend almost every waking moment trying to be part of the solution that caused the tragedy in the first place.”

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Neil Heslin, Jesse Lewis’ father, in March 2013
| Credit: John Moore/Getty
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Scarlett Lewis, Jesse Lewis’ mom
| Credit: Peter Kramer/NBC/NBC NewsWire/Getty

Echoing the sorrow of her son’s father, Scarlett says Jesse’s death was “like losing a limb.”

“He’s still always with me, even though it’s kind of spiritually,” she says. “But you always have that longing. Always. It’s always, every day.”

The pain doesn’t dull, but they persevere.

“J.T. and I try to honor Jesse’s memory together by having a lot of fun,” Scarlett says. “Jesse left a little note for J.T. It was about this big, and it was folded up, and on J.T.’s desk. And J.T. came back to the house after the tragedy, and found this little note and unfolded it, and it said, ‘Have a lot of fun.’ ”

“One of the key things for me, I knew I had to accept what happened and move forward and to be able to go on day by day,” Heslin says. “And I accepted it right when it happened. I didn’t like it, I knew I couldn’t change it, but I wasn’t going to let it ruin my life or destroy my life anymore than it already has.”

“It’s really important to stay busy, keep your mind active,” he says, “even though you always find yourself in the distance a lot just thinking about Jesse.”

By KC Baker and Adam Carlson