After committing a series of brutal rapes, a young man must conceal his crimes when he supernaturally begins to feel the physical pains of one of his surviving victims…. His pregnant best friend.

First, don’t give away the twist… his best friend.
Second, one assumes he’s been concealing the crimes all along.
Third, supernaturally feels odd as the descriptor.

Suggestion:
A serial rapist begins to personally experience the physical trauma of his victims.