I'm sorry to hear this. Discovering that a friend has been harmful to someone, especially to another friend, is its own brand of heartbreak.
I agree with the maxim of preserving the art, in a general sense. Whether it be their own or part of a collaboration, I do not believe in forced removal of expression, even if the creator's legacy has been altered by their actions.
Your own publications, however, are personal. It is, instead, your creation that has been tainted by someone else's actions. If you do not wish to leave them up, then they should no longer be here. I support that decision.
And I wish you well, through everything. Feel free to reach out.
Shiverwar
There isn't a whole heck of a lot I can say to you that I have not already said, but I will say this: I hope the person who allegedly did do all the grooming and manipulation and whatnot is brought to justice, and some form of finality can be reached. Your question "what do we do in cases like these" is, well, almost unanswerable to those who have either not experienced said travesties or not known anyone who has. The only thing that can be done right now is what you stated: talk about the art as well as the artist behind it. Now, I am one of those people willing to separate the art from the artist if I like the art itself, but do not like the artist, but I also agree that there are cases where the artist's actions are so reprehensible that it's nigh impossible to do that within moral reasoning. Just know that you have people you can talk to whenever and if ever you feel you need to. Whatever you don't wish to relay does not have to be relayed, and whatever you do wish to relay is up to you to do so. Stay strong, my friend.