Melanie Verwoerd says there is "a big discomfort" and "a difficulty in dealing with the second partner in Ireland".
The former South African ambassador believes people struggled to understand her place after the 2fm DJ died.
She had been dating Ryan for two-and-a-half years at the time of his death in April 2010.
"When I found him dead on our bedroom floor one morning... it caused this huge outcry in Ireland because he was so incredibly loved and famous," she said.
Her comments came in an interview on BBC Radio 4's Woman's Hour, where she said that, after Ryan's funeral, she faced huge media attention.
"Originally it was just purely because I was the 'other woman', and it is something that Ireland is struggling with, even though divorce has been legal since the 1990s," she said.
Ms Verwoerd was promoting her memoir When We Dance.
She went on to talk about the inquest into the RTE man's death.
"Minute traces of cocaine [were found] in his blood and that led to another media drama where frankly the media destroyed his reputation. A lot of it was just pure lies," she said.
Describing her former partner as "the most amazing man", she said: "I have mixed with a lot of clever people in my life but he was the most extraordinary intellect. He had the fantastic charm. He was the best listener I ever met and he was just kind and funny.
"From the first evening we spent together, it was just very clear we were soul mates and I spent the happiest two-and-a-half years of my life with him."
After his funeral, she continued to refuse to speak about him, she said, at a time when press attention was increasing.
"I have been watching the Leveson Inquiry and a lot of things rang true for me, having to face the media outside my door for months and my doorbell being rung and my children being hounded," she said.