You described my father to a T, only he drinks bourbon instead of beer. But the drink of choice doesn't matter.
My father started out this way, but as his addiction grew worse (and it does) he lost jobs over his drinking and got a DWI.
Alcoholism in a home will damage your family relationship and it will damage your children. I know you love them and you will do whatever you can to protect them, even being both mother and father if you can, but no matter what you do this will affect your children. I'm sorry to have to tell you that but I'm an ACOA too.
I think seeing a counselor is a good idea. I would also suggest that you start attending al-anon meetings. People here have varying degrees of endorsement for the program but at this point it honestly can't hurt. When your children are old enough, they can attend ala-Teen as well.
Whether or not you should leave your husband is a decision only you can make, and I would never presume to tell you to end your marriage. I know plenty of people in al-anon who have stayed with their alcoholic/addict spouses and just learned to take care of themselves and their children as best they can. Speaking from experience, I might have been happier if my mother had left my AF when I was growing up, but my mother is so needy and codependent anyway, I might not have.
I would like to encourage you to learn all you can about this disease so you can make an informed decision on what's best for you and the kids. I'd also encourage you to keep posting here, and to make TAKING CARE OF YOURSELF a priority.
Sending you good wishes and hugs.