This reminds me of my dad.....He got stopped for DUI when I was in the car and said I was driving. I was 15 though, not 4. It was one too many DUIs for him and he and his lawyer wanted me to testify in court that I had been driving. I refused, and our relationship went further downhill forever more after that. Never forgave me for not protecting him.
That's a shame. You did right though. There was no point in letting him pull you both down. He had a problem and needed to face up to it and accept the consequences.
Had you defended him, and he went out and did it again, only killed someone, you would have had to live with that knowledge.
You have my sympathies. Hopefully, you've had enough years since then to put this into perspective.
But, it is he who should seek forgiveness.. Not you. Firstly, he should have protected you against drunk drivers. That includes him. Secondly, he should have never asked you to commit perjury.
If he considers himself righteous in holding a grudge over that, he continues to have some serious personal problems that will preclude his having a healthy relationship with anyone.
People in that state of mind are destructive to themselves and to others. The only ones who can change them is God and themselves.
In my opinion, all the family can do is pray and stay out of the way.