I stopped taking note of the lines I wanted to quote after I lost count of them. They all ring right, one after another: John angry (and cussing), Sherlock waffling between diverting and really trying, and the fact that in the end, John's not so much persuaded by Sherlock's explanation as just appreciative that he finally gave one. Much better than the business on the Underground car.

Your explanation here fits mine very much: Sherlock kept everything in stasis in his head and couldn't really handle the mismatch with reality. He's not trying to be a jerk; he just has no idea how he should behave, or what John actually needs (I love the thing about the fevers, with bonus reference to Victorian times!).

"She was always much more adoring in my head.”
And the funny thing is that John wasn't—or maybe that's the John in Sherlock's head as he's returning and making a hash of everything. I think he knew he was screwing up, and he just had no idea what else to do. Good thing John was there to tell him. Eventually. When he'd finished strangling and hitting him and yelling at him.