Some of you are speaking as if you weren't murderers, but we all are (James 2:10, 1 John 3:15). It is natural to hold onto the idea that "I haven't sinned as badly as that other person," but when it comes to God's grace for salvation, dying with even only a white lie on your account sends you to eternal punishment. When you think someone else doesn't deserve salvation or deserves more punishment than you, remember you don't deserve it either. Think about how worthy you are of salvation (zero. not at all). You have worked for and earned eternal punishment. As a matter of the heart, God's forgiveness is a package gift to mankind. Either it is for everybody or it is for nobody. Which would you prefer? If you choose to deny forgiveness to someone else, then you deny it for yourself, too.
... Forgive us our debts, as we also have forgiven our debtors. And lead us not into temptation, but deliver us from the evil one.’ For if you forgive men when they sin against you, your heavenly Father will also forgive you. But if you do not forgive men their sins, your Father will not forgive your sins. (Matthew 6:12-15, 1984 NIV)
The idea that someone caused harm and is getting away with it is erroneous thinking. No one gets away with anything done in this life. God will call everyone to account for what they have done. That's all over Scripture (Matthew 12:36, Romans 3:19, Romans 14:12, ...), and it includes being unforgiving, btw. Look to your own inability to pay for your sin debt before you examine someone else's guilt.
Read Psalm 73 for Asaph identifying with the feeling that others are prospering because of their sins. Also see Psalm 37.
The truth about God, his justice, and mercy does not change based on what seems or feels right or wrong.