Kristin did it, Kristin did it. She shot J.R. and tried to frame Sue Ellen for the dirty deed.

The long, long-awaited episode of "Dallas" in which J.R.'s assailant was revealed finally aired on CBS last night, in a broadcast expected to break the all-time ratings record for an episode of a weekly series. Last May, Texas oil man J.R. Ewing was shot twice in the chest, and Dallas Fever has been spreading ever since.

The latest suspect in the case was J.R.'s own unfaithful and alcoholic wife Sue Ellen, but at 10:54 p.m. she confronted Kristin Shepard, her own sister and J.R.'s secretary and mistress, and said, "It was you, Kristin, who shot J.R."

But our long national nightmare is not necessarily over.

Because Sue Ellen (Linda Gray) spent most of the hour stumbling around in a stupor, after being booked for the murder and being released on $100,000 bail, she was only able to reconstruct events leading up to the shooting of J.R. (Larry Hagman) under hypnosis administered by her shrink, Dr. Ellby (jeff Cooper). After promising a definitive answer to the Who Shot J.R. question, the producers seemed to be leaving room for doubt over whether Sue Ellen's memory and flashback were correct.

And they cleverly threw in a new complication to keep viewers hooked. Kristin (Mary Crosby), while not admitting guilt, announced at about 10:55 that she was pregnant with J.R.'s child. And so life goes on.

Kristin had been considered one of the likeliest suspects, and in fact it may have disappointed regular fans of the show who expected a shocking surprise. In Las Vegas, where betting was heavy on the outcome, the odds that Kristin pulled the trigger were 3 to 1 yesterday, before the show aired. The odds on J.R.'s brother Bobby (Patrick Duffy) were 5 to 1, and the odds that J.R. shot himself in a fit of spite were 15 to 1.

CBS charged advertisers a reported $250,000 for 30 seconds of time on this much-ballyhooed episode, delayed from its originally scheduled air date by an actors' strike in Hollywood. That means that by 10:30 last night, the halfway point in the show, the CBS take was already $1.5 million and by the end of the show $3 million. CBS probably made $2 million in profits on this single hour of closely watched television.