When she seems receptive, you may also want to point out to your wife that not everyone who is da'd or df'd committed a sin. There are many of us who left to escape severe physical and/or sexual abuse. There are many of us who simply stopped believing. As for your dislike of the bitter people on this site, (which I am one), you must understand that being prevented from having any contact with our family members who are still in, makes a person very bitter. Can you imagine what it is like to have to leave the organization to escape physical or sexual abuse within the organization and then have your family turn on you? It hurts, and though the pain lessens, it never goes away.
As for people who were da'd or df'd due to sin, didn't Jesus say, "Let he who is without sin cast the first stone"? For the most part, jws are so busy with being concerned about the sins of others, they don't have time to look at themselves or the crooked leadership which they are following.