I'm not excusing his behaviour at all but humans are a weird animal and often hit out at others rather than see face up to things. Maybe as your dad he feels guilty he didn't 'protect you' from life's pitfalls.
My dad was an alcoholic and used to tell me it was my fault for being such a difficult child - I was about 12 at the time!
His comments have very understandably hurt you but him feeling he had to say it shows he has 'the issue' so he needs to man up and sort himself out - you've faced up to your own demons which is mega!!
Putting myself in his girlfriends shoes, boy would I have ripped him apart when we got home!!
Xx