And in the years since, Kemmerling, now a 19-year-old sophomore at Arcadia University, has managed to rise above the harassment that thousands of gay students go through every year - and that once nearly drove him to suicide.
He created an anti-bullying Facebook group that attracted more than 1,000 members, and worked with an advocacy group as a student ambassador.
He appeared on national news shows to discuss the effects of teen bullying.
And on Friday night, the latest chapter in Kemmerling's story will air in a documentary produced by the USA Network and the NFL, when Kemmerling discusses bullying with New York Giants wide receiver Victor Cruz, who dealt with racial harassment growing up.
Kemmerling called the meeting with Cruz "inspirational," and said, "To share my story and hear his, it had a big impact."
After coming out to a few friends in eighth grade at age 13, Kemmerling, from Warminster, didn't know that his secret had spread around school.
A few weeks later, he said, he was confronted in the locker room - shoved to the ground, called derogatory terms, all out of view of an adult.
"It got to the point where I feared the locker room," he said.
The bullying continued elsewhere - he transferred schools four times before graduating in 2012.
And in 10th grade, he told his mother he wasn't sure he wanted to live.
"I cried in her arms," he said, "and I told her I couldn't do it anymore."
Advocates say that LGBT teens across the country frequently experience similar hardships.
According to a 2011 survey conducted by the Gay, Lesbian & Straight Education Network, more than 80 percent of middle school and high school LGBT respondents reported being verbally harassed because of their sexuality.
Nearly 40 percent reported being physically bullied, the survey says, and almost 20 percent reported an assault.
"Youth who are perceived as being different are often targets," said Emily Greytak, the organization's director of research.
"There's tried-and-true interventions that work" to reduce bullying, she said, such as student-led equality groups and school anti-bullying policies.
But bullying levels, she said, are "still too high."
Kemmerling said his parents, counseling, and a theater program helped him.
And in high school, he started a Facebook group to write about the effects of bullying, which grew to attract more than 1,000 members, and eventually turned into the Equality Project, a nonprofit advocacy group.
As it evolved, Kemmerling shared his story through local TV channels and once on CNN, and he became a student advocate for the Gay, Lesbian & Straight Education Network.
After high school, he said, the bullying seemed to disappear. And at Arcadia, he has been able to live like any other student.
"I am not a victim," he said. "There was a time in ninth, 10th, grade where I needed help, and it just wasn't there. But I am not a victim."
The discussion with Cruz, which will air at 7 p.m. Friday on the USA Network, took place in the Giants' locker room.
In high school, Kemmerling would change for gym class in the nurse's office because he feared the bullying inside locker rooms so much.
But a lot has changed since then, Kemmerling said.
"I did work through this," he said. "My hope is that in the future, kids will not have to go [through] what I went through."