yes. Was the money that was in there on the date of separation collected entirely during your marriage? If yes, he is entitled to half, if no, it will only be half of the portion that was added after marriage plus the gain or loss.
If you took it out after separation they will see this transation if they supenea the records. They may just ask for the balance at separtation, if so they will get the information prior to you hiding the money. Either way they will find out, just tell them the truth it will look better to a judge if it has to go to court. Hiding assets is a very serious issue in a divorce, yes people do it and get away with it and other try and are found out, why risk it? Like I said previously, no amount of money is worth my freedom.