Sonya answers him "accept suffering and redeem yourself by it". Sonya is very religious and very faithful, she is telling Raskonikov to confess in order to be redeemed, and in order to get rid of guilt.
Raskolnikov is feeling very guilty, and this guilt inside of him, makes him want to try to commit suicide. He is not only feeling guilty for the crime he has committed to the pawnbroker and her sister, but he is also feeling guilty towards his family. He is trying to help his sister, and his mother, but he is not able to after this murder he has done. Raskolnikov is feeling hopeless, and life has no meaning to him. Even though he will confess, and go to prison in Siberia he will still be feeling guilty and be blamed for the acts he has done, he will never forget the murders of the landlady and the sister. .
This guilt of Raskolnikov connects to the guilt of Gregor Samsa in The Metamorphosis. Gregor Samsa is a traveling salesman who hates his job but is forced to keep his job in order to support his family. He is working to pay off his father debts. One day Gregor wakes up and finds himself transformed into a giant insect. He is struggling with the feelings of guilt, because he is unable to support his family after his transformation, as if his inability to support is family was his fault. Greogor is now a burden to his family, he is being isolated and neglected from his family, his family is disgusted by his metamorphosis. Guilt is Gregor's most powerful emotion. Every time the family mentions money, he feels guilty by losing the ability to support his family. Gregor really hates his job. He hates having to worry about traveling, he hates the way his boss treats him. Greogr is being alienated from his family, his job, and himself. Gregor is like a slave to his family, forced into hated labor, he is feeling no bitterness, and his primary feeling is guilt. .
Gregor clearly feels guilt, he is not realizing that the situation he's in is out of his hands.