तानहं द्विषतः क्रुरान्संसारेषु नराधमान् ।क्षिपाम्यजस्रमशुभानासुरीष्वेव योनिषु॥
tān ahaṃ dviṣataḥ krūrān sansāreṣu narādhamānkṣipāmy ajasram aśubhān āsurīṣv eva yoniṣu
Word by word
The verse says
Those who hate, who are cruel, the worst of people, bringing nothing good - I throw them again and again, in this turning world, into demonic births.
In plain words
There is no softening this, and pretending otherwise would be dishonest.
Krishna says he throws them. Again and again. Into births of the same kind.
The one thing worth holding before you read on is what the sentence is made of. It describes a consequence, and it describes who is handing it out, and those are two separate claims that the traditions have never agreed on.
Where you've felt this · in growing older
You worked for thirty years alongside a man who was difficult with everybody. He retired eight years ago. Nobody from that office has called him once, and he tells people he never liked them anyway. No one punished him. The thirty years simply arrived, in the shape they were always going to arrive in.
Going deeper
This verse has been used to do real harm, and the first honest thing to say about it is that.
Taken as a sorting of human beings, it licenses almost anything: name a group as demonic by birth, and the text appears to say God has already thrown them away. That reading has been made, and acted on. It does not survive contact with the rest of the book. Earlier in this same chapter the condition was one anybody can enter. Two verses further on, the three ordinary doors into it are named - wanting, anger, greed - and anybody at all can walk through those. A condition with public entrances is not a caste.
There is also the question of who does the throwing, and here the traditions genuinely differ. Read one way, this makes God an active judge who sorts and discards. Read another, it describes the plain working of action and consequence, with Krishna speaking as the one in whom that working happens - much as you might say gravity drops a man, meaning no malice by it at all.
What is not in dispute is the direction. Cruelty feeds itself. It builds the character that makes more of it available, and nothing outside is needed to keep that going. If you want the warning in this verse without the misuse of it, that is where the warning lives.