Sorry to say but there's a good chance that this person already has your resume, sees where you're now working, already asked the spouse about you, so your cover is blown.
I've made mention that I'd like to get another job to a vendor at one point, some years ago. That vendor mentioned this to someone at an unrelated company to an unrelated person. That one talked to someone else, who talked to someone else and about a month later, my manager asks me to come in his office, closes the door and asks me about why I'm looking for a job.
I'd go ahead with the interview because that horse left the barn already, so you might as well find yourself a new landing point before the old one gets yanked from under you.