I disagree that she did. Stumbling onto someone else watching child porn and seeing a bit of what that other person was watching is not a crime. The husband very likely committed a child porn offense, however.
That simply means they didn't have sufficient evidence to warrant going further; it does not mean it wasn't a crime. You may also report this to the FBI since downloading child porn over the internet is a federal crime. Perhaps the FBI will take more of an interest in it.

