When you file for divorce, she will have to account for the money in that joint account during asset division. If she used it to cover household expenses over the time of separation, that is ok. If she used it to buy her boyfriend a rolex, that's dissipation of marital assets.
I suggest you save up over the next year so you can have a lawyer for your divorce.
I suggest you save up over the next year so you can have a lawyer for your divorce.