Should i continue to have lunches with ex clmate who has expressed interest in me?

met an old clmate and had a few lunches with him and he has asked me to be his girlfriend. By the way, both of us are married. I have told him in no uncertain terms that i do not wish to be one but do not mind having him as a good friend, i still want to see him for lunches as i do not wish to taint the firendship becos of this..should i still see him for lunches, concern that he may got the wrong idea..