How about you help me figure out how to get over my fear of screwing up AGAIN, at 40, and I'll try to help you get over your fear of starting fresh? :-)
Honestly, you're doing this at a great time, as others have said. I won't go over what they've said. "Non-traditional" students aren't unusual at all now, especially in online classes! I just switched to online classes myself fall semester, and I love them.
Considering what you've already achieved in your life, I'm wondering why you'd be so afraid of this? You've already developed self-discipline - you must have. You know yourself, far more than any 18 or 19-year-old could. You know why you're attending school, and what you want to do with that degree, right? You must be pretty motivated!
And if I can FINALLY be finishing up my BA now, after starting at 17 and being in school off and on over 23 years, I am 100% sure that you CAN do this. I dropped out and gave up a National Merit Scholarship to put husband #1 through school. We divorced and I tried to return to school, then had to drop out again because of work and health issues. I went back again a couple of years ago, but have struggled constantly with health stuff and had to totally drop all of my classes in early 2005 because of them, and I felt like a total failure.
When my daughter decided to try high school this fall after being homeschooled for the last five years, I was so lonely that I tried one more time. My current school splits things up so that you take a full load, but semesters are split up into two 8-week sessions, with only two classes per 8-week session. I don't know why, but I find it easier to deal with things that way. (I have some cognitive issues due to my disability, and switching gears between two subjects seems to work better than four!)
With a LOT of support from my life partner and daughter, I've got a 4.0 so far. The first 8-week session was hellish, but 1) I had my first math class in over 20 years, and it was statistics (yipes! I have a math phobia!); 2) they were face-to-face, rather than online, so I was so exhausted just from GETTING to class that I was hardly conscious DURING class; and 3) it WAS my first term back in school and I was adjusting to a new school that was way different from any that I'd attended in the past. But I still got all As! (Okay - I have OCD, too - I can't handle anything but all As, so I nearly put myself into a health tailspin getting those silly As.)
If someone who is older than you, has a mind like the finest sieve, and who has failed at this college thing (mumbledy mumble) times can do it now, YOU CAN TOO.
Don't be silly git like me and have nonsensical expectations of yourself - Bs are totally cool. In fact, passing at whatever grade you need to get to keep any financial aid or other assistance you might have, or to meet whatever goals YOU have set FOR YOURSELF, is all you have to do!
So pace yourself, be good to yourself, and give yourself time to adjust to this new thing. Remember that you need time for the things you did before AND school AND fun!
Good luck :-)