My sister's husband is playing with her emotions. What should she do?

While they were on a family visit to my home, her husband deserted her, sending an SMS that he cannot live with her and is leaving her, inspite of no quarrel. He sent the same message to my parents and all of us have been thinking what to do. He took a flight and went to his place, took his things and is still missing. Over the years, he has used her emotionally and financially as she has a much better job than him and earns significantly. For past 1 year, she has started managing her account herself as she was left with no money inspite of earning high.What should my sister do?