In The Outsiders, what made Johnny feel so terrible?

There are several moments throughout the novel where Johnny is feeling terrible about a situation, event, or comment directed towards him. In Chapter 6, Dally comes to visit the boys at the abandoned church and takes them out to eat at Dairy Queen. Johnny makes the comment that they are going to turn themselves in. He says that it isn't fair to Ponyboy's brothers that he is gone. Johnny mentions that they must be worried...

There are several moments throughout the novel where Johnny is feeling terrible about a situation, event, or comment directed towards him. In Chapter 6, Dally comes to visit the boys at the abandoned church and takes them out to eat at Dairy Queen. Johnny makes the comment that they are going to turn themselves in. He says that it isn't fair to Ponyboy's brothers that he is gone. Johnny mentions that they must be worried sick about Pony. Johnny then asks Dally if his parents asked about him. Dally snaps and says that they didn't. Pony mentions that Johnny is taken back and doesn't say anything. Johnny stares at the dashboard in bewilderment because he feels terrible about the fact that his parents do not care about him.

Another scene in the novel that depicts Johnny feeling terrible takes place in Chapter 8 while Johnny is lying in his hospital bed. Ponyboy attempts to cheer Johnny up by telling him that he'll be okay. Johnny laments to Ponyboy about how scared he is. Johnny tells Ponyboy that he doesn't want to die because there are so many things he has yet to experience. Johnny feels terrible about his condition and believes that he is going to die soon.