What does 2 Samuel 16:8 mean?

'The Lord is paying you back for all the blood you spilled in Saul’s family. Now he’s handed the kingdom over to your son Absalom. You’re getting what you deserve, murderer!' 2 Samuel 16:8 - Modern Text Bible

(Shimei claims David is finally facing justice for his actions against Saul's family, saying God is punishing him by letting Absalom take over.)