Good job on getting the rabbit away from the cat. That's no easy job. If the rabbit is alert it should be released where you found it. If you think the injuries are severe enough that it cannot be released, it should be sent to a wildlife rehabilitator. In TX you can find one at:
http://www.tpwd.state.tx.us/huntwild/wild/rehab/list/ I'm not sure what the law in Texas is for keeping wild rabbits as pets (it's illegal here in IL without a permit). So if you are still thinking along those lines, it would be worth checking into that.