Complex sentence: When it became clear that Tony's men would not allow themselves to be imperiled for no good reason Tony was forced to act, Tony murdered his own cousin to save his family and give Blundetto a quick and painless death.
Split into simpler sentences: When it became clear that Tony's men would not allow themselves to be imperiled for no good reason Tony was forced to act. Tony ultimately murdered his own cousin to save his family and give Blundetto a quick and painless death.