Bunz stumbled on his way into court in Buffalo and was helped to his chair by deputies. He pleaded guilty in July to first-degree manslaughter.
Bunz had faced a more serious second-degree murder charge, but prosecutors agreed to the plea because of his age.
He admitted hitting 89-year-old Virginia Bunz about 30 times with a hammer after the couple argued in March at the retirement village apartment they shared in the suburb of Amherst.
Bunz, a retired chemist, was admitted to hospital briefly after the attack for injuries described as self-inflicted.