Ok. This chapter is pretty much almost impossible to summarize because it is basically just one long running monologue of crazy.
Let's back up for a second.
So, it's the next day, and Myshkin waits for General Ivolgin to come see him at the appointed time. When the general shows up, they first talk about Lebedev and how the general will never speak to him again because he is a huge jerk. General Ivolgin never mentions the actual reason (that whole wallet thing in the last chapter), but instead says that Lebedev keeps telling outrageous lies about his past and the situation is intolerable.
And boy oh boy is this ever a case of the pot calling the kettle black. Next thing we know, General Ivolgin launches into the most amazing performance of his one-man play of delusional insanity, called During the War of 1812, When Napoleon Occupied Moscow, I was his Chamber-Page.
Which, um, is so, so clearly not true that it's beyond impressive to see the level of detail the general manages to get into. Basically, he's concocting a pretty good historical novel about a little boy witnessing big moments in history just like that out of thin air.
This goes on for pages and pages and pages—seriously, this is one of the longest chapters in the novel, mostly we think, because Dostoevsky kind of began to have fun spinning this bravura performance.
Finally, Myshkin manages to calm the general down and they seem to part on good terms.
But the next day, General Ivolgin sends him a short note saying that he's no longer going to be friends with him. Myshkin assumes that this is out of embarrassment.
And so, the day after this happens is the day when General Ivolgin storms out of the house.
Kolya goes out into the street with him, hoping to calm his down.
Just as this seems to be working somewhat, General Ivolgin has a severe stroke.