Nancy - I can only second TL's thoughts. You did *far* more than babysit. You gave her the chance to have a different kind of life, to *not* repeat the cycle. It's so sad that she didn't take the chance, but.... you gave her the opportunity.
As I'm in the homestretch here with- all my kids, in terms of active parenting, I have to say the hardest thing is to watch them start making their own (bone-headed) choices. Must be the control freak in me

, but there are some days I just want to smack them
all upside the head and ask them if they ever paid attention to a single thing I tried to teach them. Mostly I just bite my tongue - I'm very quiet these days, LOL.
We've said it for years - from the time our kids were acting out in school, through police involvement and all their other lousy choices - their behavior, their choices, are *not* a reflection of our parenting. You know you did your very best to teach J good values, modeled how to live a responsible adult life, sought out resources to help her be a decent, law-abiding, healthy adult. The path that she's on right now is not because of any failure on your part.
You were/are a far more vital part of J's life than just a babysitter. You may not see the imprint you had on her, and she probably won't admit it, but.... I believe with all my heart that she's got a much better chance of getting her life together, under any circumstances, than she would have without your and husband's influence.
Many many gentle hugs to you.