What does it really mean to be “released”? How does Jonas react to this knowledge? How will this change his relationship with his father after seeing the release of the twin?

Released is a euphemism for death. Release is the term used when members of the Community are sentenced to leave (actually, sentenced to death by lethal injection). In reality, the people being released are injected with a lethal injection of CYANIDE CHEMICAL, and their bodies are thrown away. Jonas is horrified. I think Jinas has already began drifting apart from his family. This news will actually sever any bond he has left.