Hiya. There have already been some awesome posts on here, so I won't bang on too much.
As others have said, you are the one who has to deal with your pain, so the choice is entirely yours and should be made knowing everything you can find out about each option.
My thoughts: If I were in your position, I would try for the VB but with an epidural. If you are unable to move with your back pain, that would make labour difficult because labour pain can be eased by moving around and it sounds like that wouldn't be a viable option for you.
As bx has said, you are no doubt a whole lot tougher than you give yourself credit for. The fear you are feeling is natural but unwarranted. You can do it, but you need to believe that for yourself.
The last thing I'll say is that there is no way I would choose surgery without at least giving VB a try. (Just tossed that in because you asked what we'd do. But as I said, the choice belongs to you, and no one around here will judge you for it.)