Joint Bank Account Problems

What is the name of your state? New Jersey

My ex and I had a joint account (which I still have but am closing this week). The only reason I haven't closed this account yet is that I have direct deposit and am waiting for my next check to go in first. Last Friday when my check was deposited, I went to take out money and someone (I know it was my ex since she has a card and is able to do so) took $400 from it! Although this is a joint account she never put money into it, we just made it a joint account so she could write checks if need be. When I asked her if she took the money she denied it, of course, and then when I spoke to our landlord about the last payments on my apartment he had told me that she already gave him a check for $478 and that she told him I would write him a check for the other half of the amount due...but how is it fair that I pay for both halves since I KNOW that the $400 she gave the landlord was my money!?! Is there anything I can do and if I don't pay the rest of the amount off will this affect me?

[Jeter]

Since she took money out of a joint account that bears her name, there's nothing that you can do except close the account and open one in your name only. In the eyes of the bank, it is equivalent to saying "that $10 is mine and the other $10 is hers". It doesn't matter. In a joint account, all funds are treated as joint funds. You gave her equal power to make transactions in the account and then deposited your own money while she still has a debit card. If she's trying to screw you, she has succeeded and your landlord I'm sure doesn't care if Santa claus writes the other check as long as it clears. Your landlord may be able to contact the CRA's and report non-payment of your rent, so it can affect your credit rating if you don't pay the remainder of what you owe.

Thanks for the advice! I am definetely closing that account!