FARMINGTON, N.Y. AP – They met in a Veterans Affairs hospital, a former airman with bipolar disorder who drank too much and a clerical assistant struggling to cope with her teenage son’s drug-overdose death.

Cynthia Galens and Thomas Stack soon moved in together, and their two-year relationship seemed to mirror his roller coaster battle with alcoholism. Galens says Stack was emotionally and physically abusive, and she decided one night to exact revenge by lacing a jug of margarita cocktails with antifreeze.