Welcome to Healthcare Magic forum.
Your sister seems to be having a psychological problem causing paranoid thoughts and jealousy, anger, depression etc.
This is common in people suffering from any disorders like manic depressive disorder
, obsessive compulsive disorder
or a personality disorder
The best way to confirm the diagnosis and start apropriate management is to consult a psychiatrist
who after detailed examination can solve her problem.
Please do not delay the consultation as in such cases the situation often worsens as time goes.
In most cases the condition improves with medications like antidepressant or anti psychotic medications and psychological counselling
Hope this answers your query.
Wishing her good health.