Major depression. The house! pls advice.

My wife has been suffering from severe depression for the last 4 years.This depression was brought on by her mother's death , followed by brother's sudden death , sale of family house & now compounded by the imminent departure of our son for his studies abroad.She was referred to a psychiatrist who prescribed anti depressants about 8 months back . She stopped taking them without completing the prescribed course.I have been trying to convince her to continue her treatment but she is just not ready to listen.Over the last few months she has totally lost it & has tried many times to injure herself physically . Our marriage is in the doldrums .Her brothers & sisters live abroad & no one is ready to interfere , bcoz they cannot stand each other .They have a family history of similar depression , OCD's , etc.They expect me to take care of her till death do us apart ! I am left with very limited choice with 2 teenaged kids in the house ! Pls advice .