If we're to have the death penalty, then this is exactly the sort of case it should be used in. Just because she got someone else to do the physical deed does not make her any less guilty of premeditated murder. If it didn't, then by that logic Hitler didn't personally kill any Roma, so he shouldn't be held responsible for the Porajmos.
Are you drunk? You're comparing her to a dictator who had actual political and judicial power and decisions over life and death. You're comparing her to f-cking Hitler. What 'power' did she have to 'make' her boyfriend kill her husband? He also escaped the death penalty by testifying against her.
Yet you think executing a woman who didn't actually kill someone herself is 'exactly the sort of case' that the death penalty should be used in? Go home.