A 65-year-old registered nurse who helped a heartbroken man end his life pleaded guilty Friday to assisted suicide and was placed on two years of probation. Kristie Jane Koepplin of Peoria, Arizona accepted a plea deal that dropped a murder charge against her. She was also sentenced to 364 days in jail, but that was put on hold as long as she completes the terms of probation. Koepplin injected a lethal dose of drugs into 57-year-old Matthew Pete…