We all drink/drank because we wanted to & at the time that was the most important thing in the world. Its that simple. But this is a very hard concept to understand by a non-alchoholic!!!! There are many reasons why people start to drink, i cant say why ur ex does but the above reasons r probably why he still drinks & doesn't want to stop.
I drank because i liked feeling drunk, i liked being the life & soul, i liked feeling confident, i liked the feeling of calm after putting the kids to bed. I liked coming home after a hard day at work & having a massive glass of wine & feeling the toasty warmth run through me, the list could go on.
He has given u the perfect opportunity to walk away....take it