Jane Holmes was told by her second husband to "choose Westlife or [him]", according to The Mirror.
The 44-year-old, who separated from partner Norman last year, has eight tattoos and has spent £30,000 on 60 of the group's concerts.
Jane revealed: "I think he thought I was joking but he soon realised I wasn't. I always get stopped in the street and he couldn't hack the attention I was getting.
"The concerts take up a lot of my time and money. Westlife are a really big part of my life. I'm completely devoted to them and the tattoos are my way of showing my loyalty. I like to think I am their biggest fan.
"It's my only hobby. I don't smoke, I don't drink, so Westlife are my only addiction."
Nicky Byrne, Kian Egan, Mark Feehily and Shane Filan announced Westlife's disbandment last month after 14 years together.
Recalling the news, Holmes added: "When I heard they were splitting I was devastated. I threw my phone down and cried. I love them for the music - and they are quite hunky."
> Westlife to split: Five career-defining songs - video
> Westlife's Mark Feehily to launch solo career
Watch the video for Westlife's 'When You're Looking Like That' below: