Why does Lennie kill curlys wife?

First off, Lennie is obsessed with touching very soft objects. Plus he becomes scared easily. So, when Curly's wife tries to seduce Lennie, he touches her hair and notices that it is very soft. She starts to try to get away but Lennie won't let go of her hair. Eventually she starts panicking and screams. Lennie, being very scared at this point, thinking that someone will hear her wails, breaks her neck. Now, this was very easy for him since he was very strong and big. If you've ever read the Harry Potter series, picture Lennie as a beardless Hagrid.