For whatever it's worth, you are not the only one to experience these problems. Unfortunately, the situation is very difficult to address.
First, let me address the woman who had the memory stick. I'm sure you have no doubt that this woman is behind the spread of the photos. Additionally, I'm sure you're right. The problem is that there is a difference between what you KNOW and what you can PROVE. I suspect she would deny giving the pictures to anyone (in fact, I would think the police asked her and she denied any knowledge). As the memory stick was lost several years ago, anything could have happened; the husband could have taken it, so too could the kids, neighbors, family or friends....there are just too many possibilities. In short, it's highly unlikely anyone will ever be prosecuted for what occurred.
Next, let me address the pictures on the internet. You should spend some time trying to find your pictures. You mentioned Adultfriendfinder, look for other such sites and see if you can locate your pictures. Anywhere you find them, contact the site and tell them that they are using pictures of you without authorization and demand that they take them down. I'm sure they will do exactly that.
I know this is not what you want to hear, unfortunately it is the situation you find yourself in. This is one of the unfortunate side-effects of the internet age, many things are very easily spread around the world and the legal system just hasn't caught up with the technology.
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