I think - although I've no direct experience of it as it, so know nothing really - is that once they truly are remorseful and the fog of depression clears and, who knows, but the hormones probably balance themselves again also - they are desperate. We can only guess at what it must feel like to have been in a place where there was no joy, only pleasure-seeking; no self-confidence, only bolstering on external things to make one's self appear temporarily OK; and utter confusion and despair because of what's been done.
They know what they've done, once the awakening occurs. I think that if, at that point, you still see them as selfish, messed up human beings and that's it, then don't bother to stand. They are going to need love, acceptance and, yes, help, to make the return.
This is such a core topic, and a really interesting one. I think RCR's articles on Agape and forgiveness apply! As someone famous once said, 'To understand all, is to forgive all.'
If you haven't yet reached a point of forgiveness yet, read, read, read - and learn. And then decide.