Regarding the other questions you'd ask in the PM - I am posting it here so that others can clarify things too, if needed.
This is assuming you are using Bitcoin Core (Bitcoin-QT is what the older versions were called) and probably what he was using:
1. The password is most likely the password to the wallet.dat file - if you have a copy of it, you should be able to unlock it with that password. That just unlocks the wallet.dat file. If you and your ex shared the wallet.dat on a single computer, he could have changed the password there. Since you said he "gave you a copy" without access to the computer or wherever this copy was, he couldn't change the password. Of course if he had access to this copy and the original he could of course change the password.
2. The private keys let you spend the bitcoins. The public keys are what people can send bitcoins to. It is fine telling people the public keys, but not the private ones.
3. If you have the public keys from the wallet.dat file, then you can see what the balance is for each address and see if they are moved. They'll look something like this:
1PXQd9Fg8qZ2bC2f3dpiWLWZjXCF28euJe (this address just had a transaction in the block chain and I just picked it at random)
You can look balances, transactions etc up on "block explorers" like this:
http://blockr.io/address/info/1PXQd9Fg8qZ2bC2f3dpiWLWZjXCF28euJehttp://blockr.io/http://blockchain.info/If he was using a different wallet it is possible the "password" is a sequence of words, like "dog blue water orange etc". If the password is a sequence of words like that, it is used to derive the private keys.
Whatever you do, do not share the password, the wallet.dat, or the private keys with anyone unless you trust them 100% because they could steal the coins with them. I say that because people will ask for it, like, "Oh, send me the password and wallet.dat and I'll help you unlock it" - there are some trustworthy people of course, but there are many who are not and will just steal your bitcoins.
The things to check:
1. What wallet software is it for? If there is a wallet.dat file, it is probably Bitcoin Core. If the name is something else, we might be able to determine the software used.
2. What OS are you using? (if it is Windows 7, for example, I would be very careful if the wallet.dat is there as compared to newer versions).
3. Is the "password" a sequence of words or just something like "thisISmyPASSWORD"? (Don't tell us the words or the passwords, you can say which it is though. ;-) )
4. If the coins are still there, I'd also ask your attorney what they recommend - do they recommend moving half the coins into a different address? My concern with moving all might be that he might then argue, "Oh, see, she is trying to steal the coins". Your attorney might have good advice.