Welcome back, Acorn!
After my relapse, I was told by friends that I had to stop beating myself up and wallowing in guilt (I'm really good at that -- maybe it's the Irish Catholic upbringing!). They said it was a way of "feeding my disease".
The way it was explained to me was that our disease loves it when we beat ourselves up because then we try to medicate away our lousy feelings with a drink or drug. This was definately true for me. Then my shame would make me isolate even further. This makes recovery even tougher for me. When I feel really lousy, guilty, ashamed, I need to share it with someone to get rid of the feelings or else I begin to isolate and feel like no one has ever felt this way or been in so much pain -- that makes a drink/drug so much more appealing.
Once I do tell someone how rotten I feel though, it does feel better.
And as far as our relapses goes, well -- we definately cannot change the past. We can learn from it. I struggle with it, too. It's definately not easy.
"Just For Today" means not obsessing about past mistakes, too, I guess.