08/30/2011 at 09:00 AM EDT
may be a lot of things – but she's not a homewrecker.
In a new interview with Hoda Kotb, which aired Monday night on Dateline
, the country singer says she felt instant chemistry after meeting her now-husband Blake Shelton
years ago while performing with him. Only, there was a slight problem.
"I knew he was married," Lambert, 27, said during Monday's interview. "I had seen their wedding picture in Country Weekly
." (Shelton, 35, was married to Kaynette Williams from 2003-2006).
"I knew better," she continued, "like, this is off limits. My parents are private investigators for God's sake. I've seen this my whole life – affairs. Of all people to know better, I know better than this."
Nevertheless, the attraction between the two
– who wed in May
after dating since 2005 – was undeniable.
"I didn't know what to do with it," she said. "It was, like, my first duet with some other country star, and I didn't know if it was just initial butterflies because of that."
Continued Lambert: "I don't know what it was. It was just this draw to each other."
The couple resides in two homes
in Tishomingo, Okla., with their dogs