Morality and concept of heaven

Heaven in christianity(catholic and orthodox) is not only beyond concept of morality, ethics but also immoral in some sense. Imagine a situation: you have killed a person, normal human being, who you surely know did not go to heaven, therefore is in hell, suffering, (imagine how great their suffering is, imagine it from christian perspective, (christ says that a second in hell is unbarable) )How can u even have a will of going to heaven, when u know that because of ur sin, crime someone is suffering for eternity. What would u do as christian? You would repent and try your best to go to heaven. does it sound immoral? of course it does and it is in some sense.