I screwed up in university early on as well. I took a break of a few years. I don't know where you are, but there are a lot of universities that offer night/weekend classes. I worked full time and took classes at night. I ended up really enjoying my education because I was working and using what I was learning in class in real time. I ended up being glad that I waited and I feel like I got a lot more out of my education than I would have if I had started right out of high school.
Look at schools you want to go to, look at their schedules for a CS degree, and how much is doable at nights and on weekends, if they have special programs for adults, then start by taking one class at night or on weekends while working. In this manner you can end vacillation of whether to take the big step of going back.
