There's a lot 'him', him, him here. And me, me, me, I, I, I. 'I don't want to give up on him' 'I don't want to move on' just because of this . . .
But you have kids here who are seeing all this. They are seeing this and you are setting a role model for their future relationships. And they see you, staying with an alcoholic, compromising days out for their alcoholic step dad, doing all the work because of alcoholic step dad, themselves secondary to a relationship with an alcoholic.
'Daughter gets disappointed when we stop off for a drink on days out.'
That is so sad. It's sad that you put up with this alcoholic because he doesn't yell or get violent. Do you really think that's the best you can do? That that is something you want your kids to see and pattern their own lives on? Believe me, they know exactly what he's doing, they register the change in his behaviour.
He won't stop drinking. Why would he? He's happy carrying on like this. He's told you as much.
You need to do what's right for your kids here.