Why is Gatsby killed in "The Great Gatsby"?

He was shot by George Wilson. his wife Myrtle was ran over by Gatsby's lover in Gatsby's car. Myrtle was having an affair with Gatsby's lover's husband, Tom. Myrtle had seen Tom driving Gatsby's car earlier that day and when she seen it again she ran in front of the car trying to get Tom's to stop and get her not knowing he wasn't in the car. So she got hit. Then George finds out that it was Gatsby's car that killed her and he believed that Gatsby was the one Myrtle was having the affair with and that he was the one who killed her. So George went to Gatsby's house and shot him while he was swimming, then he shot himself.