It is not too late until physical death takes you. Then it's too late.
I had that dark voice once too. And I had a 38 to my head. Yep I was so disgusted with self, miserable and full of pain and shame, I was gonna check out. But two showed up with me; the devil, chaos and confusion, encouraging me to pull the trigger; and Jesus, calm and gentle, saying "come to me".
Well I lay that 38 on the floor. He saved me! and I was weightless, totally free of sin, and on fire for God.
You have to dig deep, find that determination drive in you and focus on the cross. He will meet you there.
All praise glory and honor be unto God. Amen