I feel similar.
Dilbert came out a bit before I was born, so from my perspective it always existed. Even before I had ever had any kind of office job, I was reading the Dilbert comics and watching the cartoon series, and had even read The Dilbert Principle.
It was upsetting that he ended up with such horrible viewpoints later in his life, and they aren’t really forgivable, but as you stated it’s sort of like a relative you grew up with dying.
I really hate my grandmother, because she has repeatedly said very racist stuff to my wife, so I haven’t talked to her in since 2018, and the only communication that I have had with her was a series of increasingly nasty emails we exchanged after she called my mother a “terrible parent” because my sister is gay, where I eventually told her that she “will die sad and alone with her only friend being Fox News”.
It is likely that I will never say anything to her ever again; she is in her 90s now, and not in the greatest health from my understanding. When she kicks the bucket in a few years, I think I am going to have similar conflicts.
Despite me hating her now, it’s not like all my memories with her were bad. There are plenty of happy memories too, and I am glad to have those, but it doesn’t automatically forgive the horrible shit she has said to my wife and mother and sister.
I have thought about reaching out, but I cannot apologize for anything I said because I am not sorry for anything I said, and I do not apologize for things unless I actually regret them.
Dunno, relationships and psychology are complex and I can’t pretend to say I understand a damn thing about how my brain works.