I get a bit tired of the 'Yoko as villain' narrative.
We'll probably never know the full story of Lennon's affair with May Pang, but John and May were adults and free agents. Yoko may have encouraged it but she couldn't force them - even the article you've linked says:
"May only acquiesced when it became clear Lennon was attracted to her after he kissed her in a lift on their way to a studio. 'Desire overcame the guilt and awkwardness,' she shrugs.
Lennon was, in many ways, a nasty piece of work. Yoko was far from perfect but she's not the monster people try to paint her as.
As for her status as a 'feminist icon' - I don't know that she herself has ever claimed to be one. She's not responsible for labels others may put on her.