It's difficult to recommend a TV movie like Ultimate Betrayal (CBS, March 20, 9-11 p.m.), since its subject matter makes it fairly excruciating to sit through. But then, that's also why Ultimate Betrayal is surprisingly worthy of respect. This film is based on a real-life case in which four adult sisters took their father to court for the physical and sexual abuse they suffered as children. Marlo Thomas, Ally Sheedy, thirtysomething's Mel Harris, and Kathryn Dowling (Ryan's Hope) portray the siblings. Henry Czerny is the father, a respected Colorado law-enforcement officer and child-abuse expert. The best thing about Betrayal is that it makes child abuse seem nauseatingly horrific, not merely the nasty bit of inconvenience that too many tidied-up-for-prime-time movies have depicted. Far from being luridly entertaining, the movie repulses with oppressive details of the father's acts, shown in flashback. Still, Betrayal is steeped in pop psychology; Eileen Heckart plays a therapist full of jargon about getting in touch with one's inner child, though the script, by Gregory Goodell, also lets us see the truth behind such cliches. All of the women in the cast deliver solid, restrained performances-in fact, this is the best work either Sheedy or Thomas has done in a while. But it is Czerny who really gives Betrayal its awful effectiveness: He's all grimly smiling evil. He is also the star of an extraordinary recent Canadian TV movie, The Boys of St. Vincent (yet to be shown on American television), in which he plays a priest who molests boys. Most actors would be afraid that two roles like this would lead to some depressing typecasting; Czerny seems to be a fearless actor, and we should be grateful for that. A-