I don't see any reason for you to talk to the father of your sons friend. It's none of your business. You weren't driving the car and it wasn't YOUR child in the car. Stay out of it.
I have often had a hard time respecting other peoples boundaries. I used to stink my nose in stuff I had no business getting involved in. But I did it because my codependency had me wanting to fix other peoples problems... And because I felt I knew best for them. All that did was make my life unmanageable. I ended up getting in the middle of situations... And then found myself getting blamed! Yikers... But I was just trying to help!!
So today, I focus on the things that are my business, the things I can control/change ( that's just me), and let every else go so they are free to live their own lives. And when I do that, life is good.
I too have had the thoughts of, "did I do enough? Was there something more I should have done (or not done!)?". But again, it was never my job to fix my husbands drinking. And now that we are divorcing... It's none of my business that his family is swooping in to save/enable him. All that matters to me is that I stay focused on MY recovery. I set my boundaries and stop enabling him. That's it. That's my job.
Thanks for letting me share,
Shannon