My sister is very sick ( in my opinion) she has an affair with her best friend husband, now she wants to divorce her husband , they have 3 children, her husband still love her very much and forgive her.
The guy told her that he will leave his wife, but i founded that is not true.
I told my sister she need professionel help, but she denied been sick.
Please help, teach me what to say and how to convince her to go see a doctor or a pschychiatrist.
She had a misscarriage with her husband a year ago.

I am desperate for any help i could get, it broke my heart, because i can tell it is not my sister that i once knew.
Anyone out there with experience teach me to solve this problem, it would be very much appreciate it.