This is a description of the castration scene in the 1988 movie Stealing Heaven, about Heloise and Abelard. It's a decent movie if you can find a copy of it.

Abelard awoke to the sheet being ripped off his sleeping body. Groggily, he rolled over to find out the meaning of the intrusion. Dark, hooded human shapes stood around his bed. Without any hesitation, two of them grabbed his arms. As Abelard twisted and struggled, still in a confused stupor, he found his voice, but it was sleep-choked and mostly unintelligible, "Hey...no...!" The man holding Abelard's left wrist put a strong arm across the top portion of his chest, also restraining his neck and cutting off most of the air from Abelard's windpipe. He gasped in ragged breaths, but was unable to speak. At the same time, two more cloaked men grabbed his thrashing legs. He felt one of the men pulling back his nightshirt, exposing his naked lower half. This had only just registered in his mind when he felt a hand roughly grab his testicles.

Abelard gasped and renewed his thrashing, but to no avail. He racked his brain for some sort of explanation for this treatment, for some sort of recognition of any of the hooded men, but he could not find either. The hand on his testicles was pulling them down sharply, away from his body and the feeling was foreign and painful. Then another robed man stepped into his line of vision and Abelard's blood ran cold. This man was carrying a menacing looking knife, very small, but curved and sharp. Even in his sleep-addled brain, Abelard began to make the connection between the pain he was feeling in his testicles and the sadistic smile on the newest man's face...

He felt another burst of pain from between his legs, like something had been tied tightly around the top of his scrotum. The hand then released him, but the pain remained in a dull ache. Abelard knew something bad was about to happen to him, unconsciously he had already figured it out, but his consciousness was blocking it, so horrifyingly repugnant the mere idea was to him. The man with the knife was now standing directly between his legs. He reached out a hand, and Abelard felt his testicles being once again pulled away from his body. He had been thrashing through the entire process (which had only taken about twenty seconds so far), but now he fought his attackers with renewed strength. While he managed to raise his body a little further off of the bed, the men easily continued to hold him down. The man lowered the knife. Abelard's eyes went wide with terror and disbelief as he felt the knife hook around the top of his scrotum...

Without hesitation, the man jerked the knife upward as hard as he could. Abelard's scream could be heard for miles. Despite the man's arm on his throat, Abelard's scream was deafening. The pain was unbelievable, unbearable. There could not be a word extreme enough to describe the pain that was radiating from between his legs. His entire body was tense, his mouth opened as wide as it would go, his eyes bulging. Abelard was in agony and his body had transformed into a high-pitched scream. The men had released him and were fleeing into the night, but Abelard was not conscious of this. Tears streamed down his face, and all that he was aware of was the pain and the emptiness between his legs that was consuming him...