I have some knowledge of you based on your post history and you're here to defend yourself. Plus, you've volunteered to participate in this conversation so you've implicitly accepted a certain level of "abuse". Thus, the first sentence, while rather rude, would come from informed opinion and could be refuted directly by the person "insulted", who has voluntarily put themselves in the public sphere. (for the record, I don't think you're an asshole)
I don't know your wife (actually, I don't even know if you have one, which amplifies the point). I know absolutely nothing about her. Thus, the second sentence cannot possibly come from informed opinion is and therefore a blind attack. Additionally, your wife has not volunteered to participate in this conversation. She's not available to defend herself, and she has not volunteered to place herself in the public sphere.
If you can't see the difference between the two, and why a different reaction is justified, I don't know what to tell you.