This isn’t the answer that will help you, nor will it especially help me, but I think it is about as close as I can come to the truth:
They probably equate homosexuality with murder, adultery, etc. So their son telling them that he is gay and not (this is my guess) about to let them subject him to conversion therapy is probably like him telling them he’s a murderer and they just have to live with it. They can’t (or so they think) and they won’t (because they don’t want to … think pride here).
Their pride is too great to “allow” their son to be just that: their son. So they possibly “give him the option” to become straight and stay with them as their son (although probably not in the sense he had been). Or, more possibly, they say “Get out of our house now. You are a stranger to us.” Maybe don’t even allow him to pack anything except Leviticus in giant font. And this in winter. If it’s anywhere near where I am, it’s still going through that snow/rain period, so he might find himself homeless and utterly in despair for days or weeks.
What utter hell to have your parents, the ones who are most called upon to care for you, turn their backs on you. I don’t even want to think about how truly wretched (which is as weak a word right now as any and at the same time the strongest I can find) that must be.
And so you decide there is one thing you can control. You can’t make your parents accept you, and the pain involved … no. Not going there. So you decide you will take the one form of control you can: control over your own life.
And so you end it yourself, because in your parents’ eyes it already is.
Poly, my suggestion to you is to pray that someone (doesn’t really matter who) show them the error of their thinking so they can devote the rest of their lives to mourning their son … he may have pulled the trigger, so to speak, but they are the ones who gave him reason.
And in time, maybe they will be able to ask God’s forgiveness, on prostrate knee, with tears streaming down their faces as they realize what an utterly precious gift they have just thrown away, for theirs was not the son to sacrifice: His was, and He did that so their son could live, even after death
And now he does with his parents’ Savior.