Good for you for helping your friend get home safely. Not only does that mean they got home safe, but it protected the strangers he possibly could have hurt/killed by driving himself home drunk. Sucks that it puts you out a bit though. Maybe set some boundaries with him. Have them set up a designated driver carpool. Force him to put a ride app on their phone or something. Explain how little fun going to a court-ordered Drug/Alcohol treatment class several times a week for months is. Get a Black Mage to Warp II them. I don't know the perfect solution.
It was just a one off, I said what was up in the post before I edited it. His dad is on deathsdoor and he got shitfaced to cope.