Complex sentence: Jason, himself previously popular, is shunned by his classmates, and after confronting and savagely beating the classmate who started the rumors, Jason is arrested, expelled from school, and all but disowned by his conservative, mortified parents.
Split into simpler sentences: Jason, himself previously popular, is shunned by his classmates. He confronts and savagely beats the classmate who started the rumors, and in the aftermath Jason is arrested, expelled from school, and all but disowned by his conservative, mortified parents.