Strongerwoman, don't be so hard on yourself. We all would have loved for our A's to turn their lives around and be the best they could be. Oh, if it were only that easy. Try and keep your chin up and look to your HP for strength and guidance. This too shall pass and tomorrow will bring another fresh day.
I agree with the posts regarding talking with your daughters. It's better that they understand WHY you haven't been yourself, instead of maybe thinking its something they have or haven't done.
Hugs to you!!