Hamlet is still angry at Claudius, still convinced he murdered Hamlet Sr., and still outraged that his mother would marry her husband's killer so quickly. But he is also torn about whether or not he ought to do something about it, namely whether he ought to kill Claudius or not. He struggles particularly at the end of Act III, scene iii because he worries that Claudius has tried to pray to repent and absolve himself and he is concerned that if he kills him in the act of praying he will go to heaven rather than to hell where he belongs.
He is also conflicted about his mother, though his anger has subsided a bit and he has resolved to chastise her and call out her wrong-doing but not to harm her as he had previously contemplated. He wants to go and see her and urge her to cease going to Claudius' bed.