In case you have not disciplined him firmly for this (just going by your saying you've had patience, and you don't mention disciplining him) This book is great; Back to Basics Discipline by Janet Campbell Matson.
My son who is almost 4 went through a pretty vicious whining stage when he was almost three, but we were able to stop it by being calm, FIRM, CONSISTENT, and systematic about not letting him act that way. Simply saying "I can't hear you when you talk like that" had no effect at all. We tried that route before cracking down on it. He just whined louder. Now he's a very sweet non whiny almost 4, and you'd never know he was such a whiner. Now my 2 1/2 year old is trying it, so the first time she lets out an anguished whine or fuss for no good reason, we give her a "Hup!" (like drill seargent style) to remind her immediately to stop the whine before she continues. It took enforcement at first, but now she gets it and stops the whine in it's tracks before speaking. No other option. Now we say, "Hup!, OK?" and she says "ok" and we say "ok?" and she starts to smile, and we say "All done?" and she says, "all done" and then I say, "What's wrong pooby, woooby" and she has long forgotten. OR, we can empathize with her tragedy AFTER she ceases the whine. By which time she usually forgets she had a tragedy. We can laugh about it now, but it did take firm discipline initially, as in firm consequence after "hup" if she still screamed or whined and we knew it wasn't a real problem. She was also taught to control tantrums, so this step is easier than it could have been, since she's used to the warning and stopping of the fit. She was a born rager too. Whatever you do, NEVER ignore it.
He needs to have consequences for constantly whining and crying and speaking disrespectfully or he won't stop. Saying mean things to M.? Hurting you feelings? NO WAY. Do not let him do that, it will make his life harder if he does not understand that respect is mandatory. My friend has a son like this, and holy cow, it's unreal! She lets him do it though. Sometimes she gets fed up and screams at him, but other than that, he has no real consequences for the action of whining all day. If you have been tough on him consistently already, I say, don't give up! But scan the book for some helpful ideas just in case. And obviously, make sure he has no medical issues. If whines more around his parents than other people, you can be pretty assured it's a discipline thing he can turn on and off.
If he's healthy and just difficult, you must persevere more than him. Don't let him outlast you and force you to allow it. 5 is pretty urgent as far as having any control over guiding his character, his habits on how to perceive life will be set soon. It's normal for some kids to act this way with siblings who don't. There's rarely a whole family full of severe whiners :) Phew. Good luck!