I have an avulsion fracture of the cuboid bone - it is very small can i use a boot and weight bear? my body won't let me use crutches

Yes : You could use cam boot and walk with it.

Hard to tell.: While a so-called "avulsion fracture" of the cubiod may represent just a small piece of bone pulled from the native cuboid, it's difficult for me to tell without seeing the films to make the call. Have you seen an orthopaedic surgeon? An orthopaedic surgeon would be able to give you a firm answer after evaluating you and reviewing your films. Good luck.