I'm sorry you feel this way. You recently got your grades so I know the wound is still open. Your life, as well as many others your age, has probably only ever revolved around school and getting good grades. AAA or death. But it doesn't, it doesn't even come close to mattering, at least in the grand scheme of things. You're too complex to be defined by a couple exams you sat at 18.
Tip: You've got to start thinking positively or you'll drive yourself mad. Think: how can I move past this while still being healthy and happy? A levels are done - move on. You got amazing GCSE grades - you're obviously extremely bright. You got BBB - good grades. You went from CDE to BBB - that's impressive! You're going to Aston University - a good, respected university. So are you seriously going to let a couple B grades at school deter you from having a great time a university and getting a First or 2.1? You've got an exciting new chapter ahead.
In short, you're only as much of a failure as you want to be.