On chapter 5 of Frankenstein, we witness the birth of the monster as well as the realization of Victor of the thing he has just done.
When he realizes the depth and importance of his project he is also encountered with its crude reality: The creature's yellow eye meets his eyes for the first time, bringing about its hideousness, its nastiness, and how wrong the whole thing is he began to develop nightmarish thoughts involving birth, the creation of life, and an overall of morbid feelings.
He could no longer function but under intense anxiety, always looking around for the monster, always exasperated and consumed by the obsessive thoughts of what he did. In all, he was suffering of guilt, fear, anxiety, and disgust of himself.
In Mary Shelley's Frankenstein or the Modern Prometheus, Victor has worked for years with the goal of reanimating flesh. In Chapter Five, when he comes to the moment of truth, seeing if the experiment will work, Victor is filled:
...with an anxiety that almost amounted to agony.
Whereas Victor had carefully tried to create an "attractive" creature, with flowing dark hair and brilliant white teeth, the reality of the monster that lies before him horrifies Victor. When he sees the breathing being he has created:
...breathless horror and disgust filled my heart. Unable to endure the aspect of the being I had created, I rushed out of the room...unable to compose my mind to sleep.
Victor tries to sleep in order to escape the horror of what he has done, but his dreams are strange and frightening nightmares. When he awakes, Victor sees the creature at the side of his bed, attempting to reach out to him, but Victor escapes.
Victor paces in the courtyard all night. When the city awakes, Victor walks about, coincidentally meeting a carriage bringing his dear old friend, Henry Clerval, to Ingolstadt. Clerval notes Victor's unhealthy pallor. They return to Victor's home, and finding the creature gone, Victor nearly goes insane with relief:
...but I was unable to contain myself. It was not joy only that possessed me; I felt my flesh tingle with excess of sensitiveness, and my pulse beat rapidly. I was unable to remain for a single instant in the same place; I jumped over the chairs, clapped my hands, and laughed aloud...when [Clerval] observed me more attentively, he saw a wildness in my eyes for which he could not account.
It is, at this point, that Victor collapses with a nervous fever, and Clerval nurses him through this difficult time. Only later does Victor begin to recover, becoming much the same man he had been before attending the university.