I don't know why I even feel bad after all we have done to help her in the past.
I know why, Rosied. It's codependent thinking, sister. Go back to Melody Beattie, and get some grounding again. It does seem that whenever an addict rears his head in crisis/using mode, we can quickly fall back into crisis/rescue mode, forgetting everything we've learned and knowing for sure that there is nothing we can do but let the addict figure out these lessons on their own. She can and will do it herself IF SHE TRULY WANTS IT. And it will only work if she truly wants it for herself, not for her boys, your son, or you.
I like that saying "I will give you the dignity to ..." and then finish it however it fits, in this case, to figure it out on your own. That way she will truly "own" her recovery, having done it by herself, and for herself.
You, meanwhile, just keep the calm and serenity going on in YOUR house. There is nothing wrong with that, and no need to feel guilty.