Hi Sara,
I felt the same way at first, I was an idiot, how stupid, how could I miss this. This is not on us in any way and we should never feel responsible for it. Though it does seem to be the first set of feelings and emotions that hit us. I think I may have had a total breakdown if I had not found this site. I have learned so much about addiction and co-dependency since then. I think you will find we all have similar stories.
I am hoping you will take care of yourself. Nothing makes children happier than seeing their mom happy and healthy. I am actually doing that for myself now and I feel really good about myself and I am getting happier every day.