How can I get my money for a vehicle I had financed?

There are two different sides to this story: the side where you are obligated to pay for the note; and then there's the side where your relative did not prevent the vehicle from getting impounded. To save your credit worthiness, you will need to continue making payments on the note. A repo (whether they can actually repossess your vehicle or not) will have a negative impact on your credit score and might make it more challenging for you to finance the purchase of a vehicle in the future. To the extent that you may want to sue your relative, you can certainly do that. If the title is in your name only, you might have claims against your relative. None of that has anything to do with your obligation to pay the note.

If you can, pay off the loan right away. The lender doesn't really want the car back. This will limit further damage to your credit scores. After that, you can sue your relative for breach of contract or conversion, but it will probably do you no good because it is almost impossible to collect a judgment from an average individual in Texas. You may have to make this a life lesson: don't lend money to friends or relatives and NEVER co-sign on a purchase for anyone.