He went home that day never thinking he would lose a job and a career he loved.
"It was really just a blur of anxiety and energy," Ruff, 40, recalled while sitting in the embrace of his husband, Ron Logan, in their Downingtown townhouse. Ruff looks different than he did on the April 21 video, with shorter hair and contacts instead of glasses. He's also shed his beard and lost 20 pounds. The change was intentional so he won't be recognized.
The couple said they've been attacked on social media, been photographed by strangers, and watched cars drive slowly past their house, and last Monday someone banged on their front door and windows hard enough to shake pictures off the wall. When Ruff went outside, he said, he saw a man and a woman in a van with pro-life bumper stickers. The man gave him a thumbs-up.
The district said in a statement: "The video speaks for itself and is a reflection of Mr. Ruff's actions that day. …" It also said that Ruff had the opportunity to present his account during a May 5 disciplinary hearing but chose to resign.
Ruff said he hoped that if he stayed silent and apologized, he would be able to keep his job as dean of academics and student life at the elite science and technology high school, where he'd worked for 3½ years. He feared that if he fought back, he could lose his teaching license.
Now, he and Logan want to give their side in the hope the harassment will stop.
"We'd like to be left alone, so we can heal and move on," said Logan, an educational consultant who has been married to Ruff for seven years. "My husband is an incredible man, the strongest person I know. He motivates and inspires me every day. We're not looking for anything from the district. We're not looking for anything from anybody."
During a two-hour interview, both teared up frequently, Ruff verging on sobs. He said he takes several medications, sees a therapist twice weekly, and rarely leaves the house without Logan. When they do go out, they eat out or shop in Delaware or Philadelphia so they don't run into students or parents.
Mostly, they want people to know that Ruff has suffered from anxiety and depression since he was a teenager growing up in Vermont, where, he said, he was abused at home, was hospitalized for two months after attempting suicide at 17, then set out on his own.
"The biggest thing I learned is, make yourself available to the people you're teaching," so he had 6:30 a.m. office hours, he said, so kids could drop by for homework help or just talk.
A measure of his popularity was the petition students created after the video came out calling him a "crucial and valuable member of the STEM community" and urging the Downingtown School District not to fire him. It was signed by 52,000 people nationwide, 8,000 from Pennsylvania, while a GoFundMe campaign raised $7,880. He has an envelope filled with more than a dozen letters of thanks and encouragement from students and parents.
Ruff said that in the months prior to the incident, his job at STEM had become more stressful. Once he even suffered an anxiety attack over a computer glitch that occurred while students were taking the Keystone Exams, and wound up on the floor in an office. Afterward, he said, headmaster Art Campbell, whom he had considered a friend, remarked in front of other staff that Ruff should wear Xanax around his neck like a candy necklace.
He was given increasingly more responsibility without any clear direction and even sought another job in the district, he said.
On the day of the protests, Ruff said, the principal was away on a school trip and Mike Sheehan, dean of curriculum and instruction, asked him to deal with the situation. Sheehan also put in a call to assistant superintendent Robert Reed for guidance.
"I was there to protect the students," Ruff said. "I wanted them [the protesters] to engage with me instead of the students."
One of the few things he remembers was making a disparaging comment comparing the protesters to President Trump.
After leaving and returning to the school office, he said, he was shaken. Later, he learned that Sheehan and two others had watched him through a window, and had gotten word from Reed that the protesters were allowed on the sidewalk. Ruff said he wonders why no one came outside to tell him that, or to intervene when they saw the confrontation escalating.
Still, he didn't think his job was in jeopardy.
The district maintains the staff watched through the window at the beginning of the incident and it appeared Ruff had the situation in hand. School spokeswoman Patrician McGlone said Sheehan texted and called Ruff with the news from Reed, then left to take care of two other issues.
Ruff said he never received a call or text.
The video shows the confrontation starting early, when Ruff pointed at the poster of an aborted fetus and told the protesters, "You can go to hell, where they are too."
When he got home, Ruff said, he wrote an email to Reed explaining what he remembered, which wasn't much. At the time, no one knew he had been recorded.
He returned to work the next week but on the night of April 26, Campbell called to tell him about the video, he recalled.
Ruff said he offered to resign but Campbell told him they would try to save his job and that hopefully "it would die out and go away," Logan said.
Campbell and Sheehan did not return calls for comment.
The former administrator still has supporters, including Ron Pavlick, a retired assistant principal whom he worked with at Downingtown High School East.
"I have always found Zach to be a person of character, I've always found him to be passionate about students. He's a good man," he said.
He didn't want to talk about the video, but said, "These are terrible situations to be in because there's no way to win. Even if you're doing the right thing, it appears to be something far less than that. … All I can say, honestly, is Zach is a good man. Hands on the Bible, he's a good man."
Ruff sent out 200 job applications last summer and had a few interviews — one potential employer ended up blocking his phone number, apparently after seeing the video — but worries he will never work in education again. "I didn't want this to define me," he said.
But there are those who still believe in him.
Last summer at lunch with two friends, he saw a parent and student from STEM. Anxious about being recognized, "I kind of freaked out a little," he said.