Hi -
Sorry no one else has replied to you yet - I hope you're still looking at the posts. I'm both a single parent as well as a professor and a university administrator whose job it is to coordinate all the academic support services to students (tutoring, etc.). Between the two, I feel pretty confident in my ability to respond to your question. In my experience, students who do not want their parents to know how poorly they're doing are the same ones that refuse to sign the "parent contact" forms (essentially the same everywhere in regard to FERPA privacy regulations). The students who are doing well don't usually have an incentive to withhold information from parents (although occasionally they may have good reason). It sounds like your daughter is using your deep desire for her to have an education against you, through emotional blackmail. Even if you do cave in and pay for it, she probably won't be successful, anyway! She needs to value her education enough to be willing to do whatever is necessary to get there and to make it work. It sure doesn't sound to me like she's there, if she's once again wanting you to bail her out - but all on her terms! She'll likely do the same thing in her coursework that she's doing to you (in my experience, immaturity, blaming, and disowning personal responsibility are the most common reasons for college failure). There are all kinds of other reasons to hold the line as well:
1. She's 21. It's time!
2. If she has to work for it - take one or two classes at a time, and work to pay the tuition - she'll value it more and be much less inclined to blow it off. My best students are often these.
3. You paid for it once. That's all the parent-contract says we're in it for, if even that! She chose not to take advantage of it when she had it. Decisions have consequences, and she's feeling hers.
Finally, the irony here is that if you pay for her to go back to school in order to help her continue her education, which you so badly want, there's a good chance the opposite will occur. However, if you refuse, and she eventually comes to it on her own, there's a good chance that she'll actually get an education, and you'll both get what you want. Strange, eh?
As a single mom I know really, really well the pull that my son can put on me, and how hard it can be to hold the line (i.e., no one is there to back me up, and given that we're very close - closer than most traditional families since it's just he and I - saying no to him can be very, very hard - and no less important!). So here's your back-up from me, a fellow single parent: NO! No, it is NOT in her best interest to rescue her again!
Good luck, mom, and hold that line!