This episode appears to be based on the 1991 Anthony Riggs case. In March 1991, Army Specialist Anthony Riggs was shot to death in Detroit shortly after his return from the Persian Gulf War. It was later revealed he had been shot by his wife, Toni Cato Riggs, so that she could collect his life insurance.
It's understandable that Denise was in a "No win" situation with her marriage. Danny foolishly spent her hard earned money and divorcing him would only cost her MORE money if the idiot claimed alimony. So realistically having a third party kill him was the only good third option Denise had to break free of the money leech stuck to her. Even McCoy was able to get Denise to admit in court that she didn't feel anything for her husband at present. The only screw up she made was killing Kovac, whose murder the cops were able to trace back to her.
Danny wastes Denise's money, so it's no wonder that she eventually felt nothing but misanthropic towards him.
Chris Noth (Detective Mike Logan) and Dominic Chianese (Judge Paul Kaylin) went on to work together in five episodes of The Good Wife (2009) portraying the characters Peter Florrick and Judge Michael Marx respectively.