Dear Frustrated Stepmothers,
There are a few ways to go with this issue, but I know it's natural and the toughest thing you'll ever have to do.
Two things as starters: This isn't forever. Stepchildren grow up, they really do leave and make their own families.
Also: Forgive yourself at the same time you open to less anxiety-driven behaviors. I know when I became a stepmother it was as if I didn't even know the person I'd become...the kind of person who had these negative thoughts.
So first has to come the love and care of yourself. Second does have to be a re-focus...or you can end up having a very unpleasant marriage. This is not to judge. I used to nastily refer to myself as the "chauffer."