The Walking Dead issue 51 page 22

Rick is having a lenthy conversation with a woman on the phone about the dire situation facing himself and Carl, and their hope to find a new group.  Rick ask the woman's name and she answers, "Rick, it's me. . . it's Lori". Rick rips the phone cord from the wall and he still continues to hear her voice. He tells Carl to pack up they are leaving. This powerful story line begins to show the crack in Rick's mental psyche. This was carried over in the AMC show.

Props to Pete Alger for picking this up this excellent page and having Charlie Adlard personalize it years ago.