BUTLER A GRADUATE OF HARD KNOCKS U.(ACCENT)

Byline: JOE LOGAN Knight-Ridder

PHILADELPHIA Brett Butler is one of those overnight successesthe kind who bursts onto the scene after 12 obscure years in what she calls the ``life-sucking vortex of comedy clubs.''

Of course, now she doesn't have to play the club scene, not with her hit ABC series ``Grace Under Fire'' (9:30 p.m. Wednesdays), and everybody calling her the ``Southern Roseanne.'' All of a suddenly the Marietta, Ga., native is having to learn to cope with fame.

``Getting this much power and attention is like handing a baby a loaded gun,'' says Butler, 36. ``That baby is eventually going to shoot himself or somebody else. I'm not …