Lily Grubb was recovering from knee surgery in a Georgia hospital yesterday when she heard on the television news that Navy Cmdr. Donal M. Billig had been convicted in connection with the deaths of three patients, one of them her husband.

"At first I thought he should just not ever be permitted to touch another patient," she said shortly after learning of the verdict ". . . I guess I really have a little more bitterness in my heart than I thought."

The death of retired Maj. William Frank Grubb was one of five that led to involuntary manslaughter charges against the former chief of cardiothoracic surgery at Bethesda Naval Hospital.

After eight weeks of testimony and two days of deliberations, a jury of nine officers found Billig, 55, guilty of involuntary manslaughter in the deaths of two patients, guilty of a lesser charge, negligent homicide, in the death of Grubb, and not guilty in the deaths of two patients.

The survivors of those five patients have filed civil claims with the Navy asking for a total of $42.4 million.

As they learned of the verdict yesterday, some relatives of those patients reacted with relief, while others expressed only frustration and anger.

Marine Sgt. Maj. Maurice Parent of Havelock, N.C., said he was shocked at the news that Billig had been acquitted in the case of his wife, Lois, who died on the operating table Nov. 2, 1984.

In that case, prosecutor Col. Gerald Miller charged in his closing arguments that Billig "clumsily tore her aorta and ended her life . . . . The standard of care was clearly violated by this arrogant, egocentric, clumsy surgeon."

Though not happy with the verdict, Parent said, "It just seems like now I can lay my wife to rest."

Billig also was found not guilty in the death of retired Lt. Col. Harold Coplan of Gaithersburg. Coplan's relatives declined to comment on the verdict.

Mary J. Kas' husband, Lt. Col. John L. Kas Jr., died in the intensive care unit in October 1984. His heart was so swollen from surgery that his chest could not be closed, and Billig, testimony showed, could not be found after the operation. Billig was found guilty of involuntary manslaughter in the death of Kas, 67, but Mary Kas said yesterday she was angry that he wasn't found guilty in all the cases.

"I was hoping he would be put away so he could not practice ever again," she said. "I wouldn't want anyone to go through the loss of a loved one like I did."

Kiyomi Estep, whose 66-year-old husband, retired Petty Officer Joe Estep, died five days after bypass surgery, said in a statement released by her attorney that she was relieved at the verdict, which found Billig guilty of manslaughter in the death of her husband.

"This decision can't bring back my husband," she said. "We hope it will deter other incompetent doctors from risking the lives of those people who turn to them for help."

The prosecution had contended that Billig, hampered by poor eyesight and a lack of depth perception, had used outdated techniques in performing heart surgery, and that he was "culpably negligent" in causing the deaths of the five patients.

In one of those instances, in August 1984, Lily Grubb stood by her husband's bedside after his operation and watched as a monitor registered that his heart had stopped. Yesterday, the 68-year-old grandmother said that until yesterday, she was in some way still hoping to find that her husband had died of natural causes, not a surgeon's negligence.

"Now," she said, her voice trailing off, "I don't know if I'm glad Frank was one of the people he was convicted of.