How to deal with someone blackmailing for committing suicide?

What step a wife can take if husband is misbehaving, having alcohol, abusing also and when a wife is also not able to leave him, because he torcher her , that if she will leave him then he will commit suicide and he will write a letter against the name of wife and her family, what kind of precaution a wife can take because it is just a torcher now but wife want to make a silent complain so that police cannot take an immediate action because wife cannot live life with this fear and with emotional torcher also.