Judy Shepard and her late son Matthew
Carlo Allegri/Landov; AP
06/26/2013 at 01:00 PM EDT
It's been almost 15 years since Matthew Shepard was lynched on a Wyoming fencepost for being gay and his mother, Judy, remembers with tears the conversation she and her son had just a couple of months before his October 1998 murder
"There had been a [news] story about same-sex marriage and he was debating it with me," Shepard told PEOPLE Wednesday after the historic Supreme Court ruling in favor of gay marriage
. "He asked me if I thought gay couples would ever be allowed to get married and he wasn't at all optimistic it would happen. He was in a mindset of, 'People are never going to accept us or understand us.' It was a much different world then. There was activism happening, yes. And we were moving on from the AIDS pandemic. But ignorance and the fear out there was its own pandemic. For Matthew, it was a very secret world still."
"I told him I didn't think I would see it in my lifetime, but he probably would in his," she said, her voice shaking. "It's so sad – and ironic – that it turned out the other way."
Shepard, who turned her grief over her son's murder into a crusade against hate crimes through the Matthew Shepard Foundation
, spoke with PEOPLE after taking some time to digest the Supreme Court decision overturning the federal anti-same-sex-marriage Defense of Marriage Act
When she first heard the law was ruled unconstitutional and married gay couples were considered by a majority of the Supreme Court to be equal to heterosexual married couples in the eyes of the U.S. Constitution, Shepard said, "Oh my god. It was joyful. It was tearful."
And Matthew was her first thought: "I wish he'd been here to see it. This case warms my heart, to think that his dream is still coming true."