No in your case that is privacy and consent abuse The nuance is in the fact that its not public , in your case your girlfriend showed you her nude in a private place and you broke her consent by publishing it in a public place. In the case of an onlyfan worker it s already public just like all the more “classic porn” that you can pay or found for free on internet. I want to add that there are no judgment in what I say ,I dont discriminate sex workers , because like a majority of people I consume porn and I would be an hypocrite to do so .