If that is the case, I might as well cut myself off from every form of media. Can something ever stop being an occasion of sin?
If the artist in question stops drawing pictures that are problematic to your call to purity, then yes. This is to say, if the artist reforms themselves and change their art as a result from say hentai or lewd ecchi to something wholesome, then yes. The reason for this is because he has changed his ways and the things he draws are no longer sinful and so are no longer an occasion of sin for himself or any of his/her viewers.
Being an artist myself, I deal with this struggle all the time, having to make sure my art which I share on the internet on art websites isn’t an occasion of sin for others, or I do my best to make it not an occasion of sin with whatever theme I’m working with.
The problem with anime style art, and indeed any art style is that depending on the artist him/herself they may be prone to drawing sensual things, sometimes out of habit or preference. What you, as a viewer, need to look out for is whether the sensual pictures are a regular theme among the artists whose work you follow. If you see that they regularly draw sensual things, like girls with big boobs and skimpy clothes, or there’s excessive fanservice then you know to avoid these artists and you can see they’re occasions of sin for you, them and their work. If you were to check back later and see their art has changed, or that they’re at least drawing something other than the sexy stuff, then I would say the occasion of sin has changed and is now determined by you, because you now have the option of picking and choosing what art from that artist, or any artist, you look at specifically. You don’t have to avoid the artist if you like their style, but you’ll know to avoid their other stuff. Most websites have thumbnails, which show you a small preview of the picture. If you look at the picture (and can see there’s nudity for example) you’ve already been alerted to a potential occasion of sin, and to not click on that thumbnail. To click that thumbnail to see the full-size picture would be to give in to the occasion of sin, and viewing the material may result in sin of some kind. How much of a sin depends on both the material itself (is it fanservice or pornographic, there is a difference) and how did you or did you not entertain the viewing of the picture.
You say you looked at a worksafe site. I’m assuming this means the hentai and nudity pictures have been filtered out. This can reduce the probability of occasions of sin, because the system reduces your risks of exposure to the inappropriate material, but it does not eliminate the possibility of running into something which may tempt you. With anime, even the clean pictures often times have some kind of sensual element, so you have to use your best judgement and senses and be aware of what you’re clicking on and what type of tags or searches you’re running.
Because a priest is not likely to understand all these things, you do not need to go into detail about it. If you know for a fact you’ve sinned, but you’re not sure how or to what extent, tell the priest you viewed the material and briefly explain the content. If they are mostly pictures of hot anime chicks, for example, just mention you viewed pictures of fictional characters, you don’t have to go into detail about it. The key is to make sure to tell him what happened as a result, as that is just as important as viewing the pictures to begin with. If you got turned on, tell him you were arroused. If you entertained the arousal, tell him this also, since he needs to know this to determine culpability factors. Lastly, you also need to tell him how much and how often. Ie- I look at these pictures x amount of hours a week, and I lusted (for example) x amount of times.
Keep it simple like this and you’ll make a good confession, and consequentially, know were you stand morally with your art viewing.