Thanks Abby...

To bring it back, a strange thing happened while everything in my relationship came to light...

My spouse's parents were unable to hide their own stories.

I'd known of an infidelity committed by my father-in-law that happened while we were first dating.
Two decades after, my wife finally asked her mother if it was with a man or woman.

The response was "woman, that time...".  She then told my wife of her own same sex attraction.

My in-laws are in a closeted, 'fake straight', non-mixed orientation marriage. 

From outside appearances,  no one would ever suspect. 

I however, suspect it to be common.  Perhaps even the norm.

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.

Shockeddaughter....Even if you do talk to your aunt and satisfy the curiosity (and I hope you do)....you should remember it wasn't your secret to hold back but your fathers and I believe you have to respect the fact neither of your parents (if your mother was aware) wanted you to know. 

My brother fathered a child with a woman wanting to replace a daughter she'd lost, and this 'secret' was known to many of us....but to my knowledge our mother never knew. Many times I wanted, after my brother died young, to give Mum the comfort of knowing of her extra grandson.....but respect for all parties stopped me.