Quit LPN school 12 years ago, now trying for RN. Help!

I am 31 years old and hold an associates degree in Liberal Arts/Humanities and Social Sciences. All that got me was dead-end office jobs that payed squat and did absolutely nothing for me. So, I have decided to return to nursing. I tried the LPN program when I was 19 and a single mother of 1. It was not a good time in my life and I quit after 3 months. I have regretted this choice ever since. I love people and know I would be an excellent nurse. After talking to this person and that person over the years and realizing if they can do it, so can't I, I decided to try again. I consider myself somewhat intelligent (my GPA when I graduated in 2000 was 3.2), but I am always doubting my intelligence and second-guessing myself. I have recently been diagnosed with Adult ADD and have a hard time with paying attention to and remembering details. I would love to hear from somebody else that maybe has been in the same situation that was/is successful. I know I can do it and refer to the future as "when I am a nurse" rather than "if", but I am still extremely scared and nervous that I will once again fail and at this point, failure is not an option.