Complex sentence: The old man accepts, but the Abbot Van Neker, disconcerted about such a wedding between a noble man and a maidservaint, decides to warn his cousin, the marchioness Lucrezia and the jealous woman, still in love with Fabrizio, has Father Tognino killed.
Split into simpler sentences: The old man accepts, but the Abbot Van Neker, disconcerted about such a wedding between a noble man and a maidservaint, decides to warn his cousin, the marchioness Lucrezia. The jealous woman, still in love with Fabrizio, has Father Tognino killed.