If she had access to the account, you can't legally sue her, even if he wanted you to have the money. Which is why you never have a shared account because one person can legally take every penny out of it and there's nothing (legally) that you can do about it.
You should have immediately had that money put into a private account under your name. I noticed earlier you said it wasn't a shared account, but if that were true, she wouldn't have had access to the money without forging your name, and that in itself is a felony.
Sucks bro, if times are hard, she shoulda came to you and asked. Her just taking it like that is flat out wrong, and not telling you about it afterwards is just as bad. My mom's been nothing but good to me so I can't say what I'd do, but that certainly sux de nuts.