Jane resists from her stepfather, because she shows signs of someone that was sexually abused in the past. In this case, her stepfather was most likely the abuser, and Jane continues to fear what he is capable of doing. She can do nothing else but cry in Holden's arms; indeed, Jane is incapable and embrassed to admit to Holden what her stepfather had done, because she is still afraid of him.
Jane most likely has some sort of troubling past with her stepfather. What that is, is never directly stated but there are enough clues that point to some sort of sexual abuse. In the previous chapter there is a remark about the fact that the stepfather was a 'booze hound' and used to run around the house naked.
because her stepdad did do somthing but jane is to scared to say so