No single tipping point I guess. I always drank a lot and it got gradually worse. It was the old story of the frog sitting in a pot on the stove with the water getting hotter and hotter.
But I guess when my dad died three plus years ago I took a turn for the darker. His only brother had nearly died in a DUI accident many years ago; dad was sent home from the navy because his brother was expected to die. He survived and drank for many more years before AA saved his life. Knowing how much his brother's alcoholism hurt the family was an inhibition to my drinking on some minor level. But when my dad passed it's like all bets were now off; there was no reason to hold back. Within a year I realized I'd be dead soon too if I didn't stop.