Or the mah na mah na song! Or do both 
Sounds like the guy was a real turd. If I were you, I’d get up there and say something like “He provided for our family and once laughed at The Muppets Show when I was a kid. Thank you.” People will get the idea that you didn’t think much of him.
I don’t think saying nice things about a mean man is quite right, but neither is focusing on his shortcomings. My dad sounded a lot like yours, Palo - he managed to alienate his entire family by the time he died (alone), but I think he had a lot of problems, too. At his funeral, we just let the pastor (I guess he was) say some generic things about him and left it at that. A funeral isn’t the time to go into how terrible he was and how he messed up his life.
Maybe you could say something like, “He was a troubled man, but his troubles are over now. Rest in peace, dad.” **Yllaria’s ** suggestion is good, too.
Funerals are for the living. Let what you say be aimed at your family and friends.
Write out a eulogy in private telling everyone exactly how you feel. Don’t censor yourself. Say everything that comes to mind. Let yourself feel all the grief and anger (or whatever it is you do feel) and when you’re done, set it aside or burn it. Maybe expressing your thoughts about this aren’t appropriate for his funeral, but you absolutely should acknowledge them somehow, because they matter and are relevant.
Then write another eulogy, a public one, that takes into consideration the feelings of others who are affected by his death. Even the most cantankerous bastard meant something to someone. If you can honor that, somehow, you’ll be doing a service to those who loved him.
I don’t think I’d say anything bad; after all, it won’t change him anymore, and anyone there who already knew him already knows the score. The only people who would be affected would be people who didn’t know him well, and they’d just think you’re an ass, rather than think he was an ass.
Nah screw public decorum, tell everyone what a dastard he was.
This. and also what Olives said. Write him a personal letter, (or a nice long Pit Post 
) and get out all the things you wish were appropriate to say at the funeral. then plan what your public statements will look like.
Important consideration: Will there be children in the audience? Will your children be there? Don’t scare them or add to their trauma, please.
but Cantankerous is perfectly OK. So is “He made a lot of mistakes, and I hope my life has been informed by them . . . I do believe I’m a better person for having known him.”
It’s also good to acknowledge his pain. It sounds like he maybe had more than the average roadblocks to contend with. Acknowledging them could help someone else to spin their bitterness into compassion. Try to think in terms of the people listening. Are some of them perhaps a bit less evolved than you are? Do you have some wisdom to share about how to turn this man’s influence to positive in their lives?
Are there things you hoped some day you’d get to share with him that are now impossible? mentioning those is OK too. If you lost hope long ago though, don’t bring it up.
End with the Muppet story. It’s enormously telling - this man who couldn’t allow himself some simple enjoyment with his children. Very sad - it sounds like he knew that he didn’t deserve it.
When my mom died, her and I had had a terrible relationship all our lives, on multiple levels. She was quite often an evil, evil witch. When people ask me about her, I usually say “She was the strongest woman I have ever known in my whole life.” That says everything I need to say - she was the strongest, including myself, which let a whole let of “my way or the highway” philosophy into her core rules. It includes negative and positive.
I don’t not say bad things if they’re true, but I try not to dwell on them. She’s dead now. She can’t hurt me unless I let her. So I try to leave them behind.
Or you could just sing it instead of delivering a eulogy.
“It’s time to play the music,
It’s time to light the lights…”
Now I’ve got an earworm. Dang it.
“Don’t speak ill of the dead.” In all seriousness, I like the “cantankerous” suggestion.
That is hilarious. Reminds me of the funeral in the Sopranos when Tony’s evil witch mother dies and no one can think of anything good to say about her.