"He kept telling me about this place he went to whenever he became unconscious," Grant Hamill, a classmate of Breedlove's at Westlake High School in Austin, Tex., tells PEOPLE.
"Every time he would go there, there would be something telling him he should come back, and that's what he thought would make him wake up."
"He told me that he's never felt anything that peaceful and it's so hard for him to come back every time." says Hamill, 18. "I think this last time he was just ready to go and he just decided not to come back."
"The waiting room, as he described it, was amazing, and he was just tired of getting a little taste of it and having to come back to where he was constrained," adds Breedlove's friend. "I think he just wanted to go see what it was like."
Hamill had seen Breedlove just two days before his death, when they spent the afternoon watching Arrested Development, and spoke with his friend shortly before he died.
"On Christmas Day he really wanted to get out and be outside," Hamill recalls. "He had just gotten a video camera [and] he went out and just started feeling out of breath and lightheaded so came inside, laid down and just passed out again and never came back from that last one."
Breedlove's parents called 911 after they saw him pass out, Hamill says, but efforts to revive him failed.
Hamill said Breedlove "was doing completely fine" last summer, when the adventurous pair had spent many afternoons wakeboarding, and that Breedlove had purchased tickets for them to go skydiving after their high school graduation. But his friend's condition had worsened remarkably over the last few months.
"His heart was just getting weaker over time and I think he was eventually going to need a transplant," Hamill said. "I know that's something he didn't want to go through."
Looking Out for His Loved OnesFor the most part, Breedlove didn't have much to say about his illness, according to Hamill, because he didn't want his loved ones to worry.
"He just didn't really like to talk about it with me because he just wanted me to be his friend," Hamill says. "But lately I think he felt it was important that he shared a little bit of what he was going through."
"It sounded like he was really ready for whatever was going to happen, and he was proud of what he had done, and he didn't want anyone to be sad for him, 'cause he was happy and happy for whatever was gonna come."
In fact, in their final discussions, Hamill said, it was Breedlove who was comforting him, not the other way around.
"He just didn't want me to be sad," Hamill said, "and he just wanted to make sure that I knew that he was gonna be okay."
No one, not even Breedlove's parents, knew he was making inspirational videos chronicling his disease on notecards until someone stumbled upon them on YouTube, Hamill said.
"It was a little bittersweet," Hamill says of his reaction to seeing the clips. "It was ... hard to see him explaining everything that he was worrying about."
But, he adds, "It was also nice to see that he was at peace and that he wanted everyone else to be."
The inspiration for Breedlove's videos reportedly came from another YouTube clip, in which a young boy who had undergone heart surgery and was also the victim of bullying holds up notecards vowing to stay strong.
"I think that smile in his last video wasn't just his enjoyment of making that video," his friend adds. "It was the fact that he was okay with everything and that he was genuinely happy."
Seeing the videos has also brought comfort to Breedlove's grieving friends and relatives.
"I wasn't doing very well for a couple days," Hamill admits. "But once I really saw him telling me for one last time that he was gonna be okay, it just it helped a lot."