Complex sentence: Francey tells Peter she will leave him unless he can change his father's mind before her train departs, and Peter decides to disgrace the family name by getting drunk and otherwise misbehaving until his father relents, even if it costs him his job.
Split into simpler sentences: Francey tells Peter she will leave him unless he can change his father's mind before her train departs. Peter's solution is to threaten the family with disgrace by getting drunk and otherwise misbehaving until his father relents, even if it costs him his job.