Thank you, Abby, for the reminder that the original poster has asked a question about her situation, and the discussion got sidetracked.  

Shocked Daughter,

   You can't, of course, ever get at the truth of how your dad really felt, or whether he acted on what you discovered, because he is no longer around to question, and he is the only one who could give you the truth. What you know is that you found a list of gay porn sites that he visited, and computers wiped clean of evidence.  Was he telling you thereby the basics but not the details by leaving that note in his bedside table yet wiping his search evidence clean?  You can only surmise.  You can also only surmise whether his grief for your mother after her death might also have been affected by guilt at his attractions to men, and whether he might have been blaming himself for her death in some way.  You can only surmise if the interactions you observed between your parents were partly your father's attempt to "perform" heterosexuality for you, what your parents' interactions in private were, and whether your mother had a private pain of her own.  You can only surmise how your father's actions and feelings about himself were affected by your mother's position about homosexuality.  All you have is the evidence that both of your parents, with you and for you, acted to give you a loving family experience. 

    From what I experienced of a closeted spouse, and how closely he holds his own secret and how determined he is that it not be discovered, I highly doubt if his sister knows anything, at least for certain.  I think it's your call whether you tell her what you've found, and ask her if she knows anything.  I'd say it depends on how well you know her.  

   I think it would be entirely reasonable, however, to express your feelings to others, in the form of "I've discovered some things about my father after his death that have cast him in a new light, and am trying to work through my feelings and questions about my family as a result of what I've found."  It's not a daughter's job to protect a father's reputation for him or preserve others' opinions of him, or promulgate a false narrative--that's what all our closeted spouses wish us to do, after all, and it causes us a great deal of pain.

  To me, it's not a question of your father being either the father you knew or the man with a secret life.  Instead, your father was a man who hid a secret about himself--perhaps from everyone--and knowing this, now, means you can no longer see your fathe--and your mother--in the light you did before you learned what you did.  That, I think, is true of all of us who are told or who discover our partner's hidden or denied sexuality.  It's painful to realize that we were lied to. It's painful to have to revisit the past under the shadow cast by formerly hidden information.   I'm so sorry you're in this painful position.

oh goodness.   Risque and provocative!  not to mention off topic - off topic?  it wasn't off topic just no longer responsive to the OP who had not replied to any of the responders on the first couple of pages anyway.  

imo, the thing people here, or probably anywhere, find hardest to take is the suggestion that gay is an inherited trait.  

It seems to be upsetting to those who have strong religious beliefs in particular.  Not sure why.  Had enough of being disapproved of for myself.  I need a break anyway so I'll say goodbye, at least for a while.

all the best everyone, Lily