In Chapter 7, George Wilson has just learned that his wife, Myrtle, is having an affair. "I just got wised up to something ..." is how he puts it to Tom. However, he doesn't know who Myrtle has been having an affair with—only that he, Wilson, is going to move with her far away whether she likes it or not. George Wilson also "learns" that the car Tom is driving—Gatsby's car—is Tom's, because Tom lies and tells him it is his.
The irony of Wilson's discovery about his wife ("Myrtle had some sort of life apart from him") occurring at the same time as Tom's discovery of Daisy's affair is not lost on Nick, who comments,
there was no difference between men, in intelligence or race, so profound as the difference between the sick and the well.
What Nick means is that although they are from completely different classes and circumstances, Tom and George are alike in being "sick" over their wives' affairs. Both men want to save their marriages. George learns, however, how little power he has over his wife when she breaks out of the room where he has locked her and rushes in front of Gatsby's car, getting killed.
The first thing that George Wilson has learned is that apparently Myrtle has been spending time with another man and so he has decided to close up the shop and move somewhere, perhaps out west. He doesn't know who the man is, only that she has been unfaithful to him.
The other things he learns are perhaps consequences of the horrible accident when Daisy runs down Myrtle and kills her because Myrtle runs out thinking the car is driven by Tom. Wilson learns that powerful and wealthy people don't face the same consequences as regular people. This knowledge comes at the horrible price of the loss of his wife, and even though he knew she had been seeing someone else, he is obviously still devastated by the loss.