Indeed, I think Chuck is one of the most truly human characters on TV today.
There’s no reason to think Chuck’s desire to torpedo Jimmy necessarily comes from one place. People don’t work that way. Chuck resents Jimmy for things that aren’t his fault, he resents him for things that ARE his fault, and he knows that Jimmy is, in fact, a liar and a cheat. He has kept Jimmy close to him because Jimmy is his brother, and he loves him, even though he hates him. That’s how real relationships are; they are a multitude of conflicting threads that connect us. Chuck believes himself to be a righteous person, and in a lot of ways he is, and he is totally, 100% correct in his assessment of Jimmy’s character. Sherrerd’s assessment of Chuck is quite good, I think; he is truly a carrier of ethics, but he is boiling over with resentment and anger that will make him explode.
Jimmy, for that matter, is a great character for the same reasons; he’s a real human. The truth is he IS a liar and a cheat. Chuck is quite right about Jimmy, and we’ve been shown indisputable evidence that he is right. Jimmy is going to hurt Kim, which will be the show’s great tragedy because she is a good person and loves him. But he’s also likeable and decent and kind in a thousand ways. And he loves Chuck. He twice put himself in danger to help Chuck.
Chuck’s decision to fight to keep Mesa Verde doesn’t really have to be explained in any way except that he’s proud and legitimately a great lawyer and wanted his company to keep the client; I do not believe he had, at the time, any problem with Kim at all. If anything he probably harbors the honest opinion Kim is too good for Jimmy, which is probably true.
As to what happens with the tape, the problem with its being released is it would result in Jimmy being disbarred in New Mexico, upon which he cannot be Saul Goodman; you can’t avoid disbarment by using a pseudonym, and he is still a real lawyer in “Breaking Bad.” So whatever else happens it does not end up as evidence in a court.
Could Chuck use it, rather than going to a cop, simply to pry away Mesa Verde? Possibly, but how? We know it cannot be used to formally incriminate Jimmy, or if so the effort will fail. Does he bring it to Mesa Verde? I agree with the assessment that they would think him mad and would find the conversation irrelevant - if anything, it just makes HHM look even more like a bunch of chumps.
So I think he’ll go to Kim with it.