What does the movie "Source Code" mean at the end, and what is the meaning of the short message sent by the protagonist to Goodwin at the end?

Because it was still 7 o'clock in the morning, the train didn't explode at that time. He also sent a message to convince her that what he said was true, to prevent the disaster from happening, and to write his own feelings about life (personally). In the end, I think Goodall believed the news, caught the murderer in time and stopped the train from exploding. So the man miraculously lived in someone else's body. At the same time, Goode also knew that what her boss was doing at this time was against natural ethics, so she terminated the plan, which was one of the reasons why the man survived.

(Pure personal understanding, forget to adopt, thank you)