A shy young girl wants to tell the real cause of her a friend's death because she was always bothered by her in her dreams but she is afraid that she might be accused of being a part of the crime and so she started to stalk her suspected killer only to realize that the death was self inflicted.

It is really wordy. If it is not vital to the story you don't need it in the log line. A shy girl risks her own innocence by stalking her best friend's killer only to discover a horrifying truth.

>>> only to realize that the death was self inflicted

The logline seems to be a spoiler, giving away how the story ends. A logline should indicate where a story is going -- but not how it ends.