It might be helpful to get the kids (I would think the 11 y/o is old enough) to Alateen, and maybe also hook them up with a counselor. They need to be educated about alcoholism--to understand that even if Mom wants to be a great mom, she isn't able to do that reliably or consistently until she gets well, and that getting well is a long process with a lot of ups and downs along the way. So it's your job to make sure everyone is safe right now. You can assure them that Mom loves them and you want them to keep loving her, but at the same time, parents sometimes have to say no when kids want to do something that might not be good for them.
You're being a good dad.