Is black magic, in India, true?

Well yes
I don't know If I should share it or not. I will tell you in real brief.
So here it goes.

6 month back, some weird stuff started happening in my neighbour's house. An 11th standard student (say s) was haunted in her dreams, for a couple of days. What she told us was there is some man, really tall who haunts her in her dreams.
No one took it much seriously. A week later, at night, around 11, S literally turned into something strange. Her eyes well totally white. Her body made some colour changes, Her voice changed drastically. I guess you can imagine what I am saying.
There was some spirit inside her body.
Yada yada yada..
Really long story..
I am just mentioning the back story. In their family's village, some rivalries were going on for long then. Some one among them, Went to a tantrik for continuous 7 days, in order to end their family ( our neighbour's).
So yeah, black magic exists.
I know I haven't really told the story well, but It will take an hour to explain everything.