Can i be sued for balance of repossessed car in Texas?

Yes. If the amount of the debt is greater than the price the car brings at auction, then you will still owe the balance, and if you do not pay it the creditor can sue you in order to recover it. Depending on how much it is and whether they think you have sufficient assets to make it worth the hassle, they may not bother, but legally they're allowed to do so.