I've been a member of this forum for a decade, and this might be the first time I have seen a post written from your kind of perspective. It may also be one of the most heartfelt and poignant posts I've seen in all these years. The words you've written not only honor your father-in-law, I also suspect they've already moved a lot of people who've read them to ponder their own situation in a new light. It wouldn't surprise me if they will save at least one person from the same fate as you hope.
For myself, I'm grateful that you shared your story. Until just a handful of months ago I was probably on the same track as your father-in-law. Luckily for me the universe stepped in - like it sometimes does - and forced me into the light. Said more bluntly, my wife found out about my crossdressing and I took that opportunity to finally come out to her after many, many years of hiding.
I think my loneliness and pain had led to my being a grumpy and mean person, but once my wife found out my secret all of that melted away and that has drawn us closer together. Words can't convey how much it means to me that I now have someone close to me that I love who is by my side as I try to find ways to get to a happier and more honest place.
Given some more time, I'm sure you would have been the same kind of gift to your father-in-law as my wife has been to me. I'm sorry that you weren't given more time with him. But instead of giving the gift directly to him, you've kind of given it all of us who read your post in his honor. So thank you for that.
Your post would be a good one to make sticky so that more people will have a chance to read it as time goes on.
P.S. My wife has an SO account here and I'm guessing she'll read this. Since it's my first post since coming out 6 or 7 months ago so I'll say hi to her - Hi!