Complex sentence: Buffy soon tracks Jonathan down, mistakenly believing that he plans to kill other students with his rifle, and talks Jonathan out of suicide, informing him that everyone in the school is dealing with just as much pain as he is.
Split into simpler sentences: Buffy soon tracks Jonathan down, mistakenly believing that he plans to kill other students with his rifle. Buffy talks Jonathan out of suicide, informing him that everyone in the school is dealing with just as much pain as he is.