Look man, if you’re asking strangers on the internet if you’re the AH or not, subconsciously speaking you know what you are. No amount of NTA from us strangers will help you. Sure your dad was a grade A AH and he shouldn’t have put your mom’s death, ignoring you at family events, etc on you. More or less he shouldn’t have lied to his now wife about why you’re both estranged. But the fact of the matter is not only were you hurt with the loss of your mother, he also lost his life partner and whenever he saw you he saw who killed his life partner and that’s a wound that just doesn’t heal.

After 27 years you should have the EQ to keep your hatred for what he has done especially when he asked you to do so. Sure you maybe boiling with anger. Sure you may think he deserves it. Sure you may now feel just desserts have been served but you do feel a tiny bit guilty that’s why you’re on this sub asking strangers on the internet if you’re an AH or not.

IMO, both of you guys are AH so my verdict would be ESH.