You said either make a dying man feel small at the end of his life or live with these things the rest of your life.
I would respond that there are other options. Say you don't have a big 'you were a bad dad' scene with your dad toward the end of his life, it doesn't follow that your only other option is to have it eating away privately at you for the rest of your life.
Unhappy memories do NOT have to eat away at you or fester just because the people involved don't change or give you what you need. Your emotional needs can be met by OTHER people - people YOU choose because they have the capacity and ability to be kind and to care. You can go to a support group. You can talk to friends, other relatives. You can find a wonderful person to share your life with. You can have a family. You do NOT have to be destroyed because your father was a jerk.
You seem to assume that your DAD has some sort of key to your happiness. He doesn't. Your happiness is up to you to create and nurture and build. It's always up to EVERYONE to do that, but because your dad was so absent from your life, I think you've lost sight of that.
You can meet your own emotional needs. You can learn how to care for your own feelings and fill your own needs. You do not need to be miserable forever or even now, because your dad was a jerk. What makes you happy? Find out and do it. What kind of person shows the warmth and attention to you that you missed from your dad? Find that person and bask in that warmth. Enjoy being loved and giving love to others. Why? Because you deserve it. As does every person. There is nothing you are required to do to make yourself 'worthy'.
First of all, those 'confrontations' with this sort of person tend to be every bit as frustrating and unsatisfying as the life you have already experienced with them. There are very few 'On Golden Pond' moments outside of the movies. Any attempt you make to get closure with them tends to have exactly the same problems you've experienced before. EVEN IF there are a few 'On Golden Pond' moments in the discussion, they are very unlikely to make you feel better for long. Why? Because they are like putting a bandaid on all that's bottled up in you.
Nor does it follow that your dad was distant because he didn't care about you. People often feel so guilty when they mess up, they have a need to flee from their worst mistakes and the only way they can function, go to work and pay the rent is by getting away from those things. Some people have very limited ability to come to terms with themselves and what they have done. They aren't trying to be mean to you at all, they just aren't very able to cope with issues and problems.
I have a relative like that. Her only way to cope with the family chaos was to move as far away as possible, start a new family, stay very busy at work. Any time I try to discuss anything that happened she gets mad at me and then I don't hear from her for months. Because of something wrong with me? No. Because she was never able to face the problems in the family. I could give many examples, but her basic way of coping was to avoid everything and anything.
She even continued the pattern of the family of playing one relative off against the other - for the rest of her life. So she was nice to one sibling and ignored the other. I've often heard from her other sibling who has suffered for years that she is ignored and treated like dirt. But it has nothing to do with who she is or if she deserves kindness or not. What it means is that this gal is so limited and rigid that all she can do is replay the events and patterns from those early days. Of course SHE is sure she has it all managed and is coping better than anyone else!
So it doesn't always follow that someone is distant because of not caring about you. Some people just have limitations in how able they are to face issues. They simply are very limited in their ability to deal with things. Their answer is to distance themselves. Their limitations are not overcome by their love for their family. Why? Because of something lacking in you? No. Because they simply aren't able.
Typically, such people refuse all counseling and therapy. They simply avoid the issues. Because they avoid help, they never get any other opinions from experts that would challenge their method. Even if they did, I doubt that they would change. They simply lack that ability.
WHY? Well, some of it is, I believe, inborn. A lot of it, they learned when THEY were young.
SO WHAT DO YOU DO?
I'm going to give you some advice.
Stop thinking that if you do A, your dad will do B and you will be happy. Stop expecting him to be something he is not. Stop trying to get him to give you what you need. Just relax.
Do what you can to spend time with your dad. I'm not 100% convinced he's at death's door based on the information provided(relatives don't always understand medical information), but whether he is or not, you do what you need to do to spend time with him.
Ignore the non-returned phone calls. Try again. Keep pushing. DO NOT turn the conversations into 'look at how miserable I am because of you'. Tell him about what you're doing today. Tell him about the things you've succeeded at. Tell him about doing things you enjoy. Tell him your strengths. Don't ask him for advice. Don't expect him to be bubbly warm or fix what came before. Just spend time with him.
If he is abusive, if he insults you and calls you names or ignores you or ridicules you, restrict the amount of time to brief visits with a purpose- give him a sweater or slippers, update him on your wedding plans. Then leave. Keep it brief. Don't discuss the past. If he brings it up, let him do so. Listen but say little.
When he passes, go to his funeral. There is a REASON human beings developed funerals. The funeral isn't chiefly for the dead. It is for the living. It gives them a time to grieve and to cry. People need that. That funeral will give you more closure than any 100 talks with your dad.
Be prepared to 'Ride the Rollercoaster' after. What I mean is you're bound to feel angry and sad and up and down and all over the place. You'll be alright, but it will take some time.
Stop worrying about what other people do. Worry about what you do. Hold your head up, and don't look to other people to fulfill you or take away what happened to you. What happened is just another part of you. You'll think about those times often. You won't forget what happened, and it will always hurt a little bit, but as you build your own life it won't hurt so much and the anger will fade away and be replaced by the good things you do and the people you love and who actually are able to express their love to you. As you get older, you'll learn to emphasize the things you learned from your family and who you are today and in the future. You'll be able to sigh and say, 'unfortunately dad was a limited person', but you won't have to be.