That he's drinking and driving now, when totally against that in the past, is the proof in the pudding.
His priorities are changing, drinking taking the forefront, example-his lying about going to the pub.
I don't have the answers as to how to get him to see that, but I think the above should relieve you of the thought that he simply doesn't love you anymore, and help put your doubt aside whether he is going down that slippery slope.
To help yourself, I would stop asking him if he has been to the pub. You already know he will lie about it, and asking him again knowing he will lie will just drive yourself mad and fuel resentment.
You will get some terrific insight here.