This is the reason many attorneys try to talk their clients out of signing reaffirmation agreements (at least in North Carolina). Once you have signed a reaffirmation, the auto lender can repossess the car AND can sue you for the full amount you owe (less the amount they sell the car for). You should see a TX lawyer to find out if you have any defenses.
Here in Virginia, the court must approve all reaffirmation agreements, As long as the court did not accept the reaffirmation agreement, you would be fine. If the court accepted it, then you are personally responsible for the debt as if you never filed bankruptcy. This is one of the reasons that many attorneys do not like these agreements. Until the 2005 amendments, they were not needed. Now, some states allow clauses that make bankruptcy a violation of the contract. In those states (Virginia is one of them), these agreements keep the creditors from repossessing the vehicle. But again, if the court rejects them, there is no personal liability.
Check with an attorney in the state where you filed the bankruptcy to see what your rights are.
When you sign a reaffirmation agreement, you are agreeing that you have the ability to pay the debt and it is in your best interests to do so. You are taking that debt out of bankruptcy protection as if you had never filed on it, so you're stuck with it and the bank has all recourse options despite the fact you were in bankruptcy. I agree with the others. That's why we (bankruptcy attorneys) hate those things. The answer to your question of "what are the chances of the bank coming after me?" is 100% guaranteed they will repo the car and come after you for the deficiency after they sell it for dirt cheap at auction.