When a pacient past away, the spouse have to pay the medical bills?

I'm not sure about whether YOU would have to pay the bills under Texas law (in NY, they would probably be considered "necessaries" for which the patient's spouse is liable), but your wife's estate is responsible for them which, if you are the sole heir of your wife's estate, amounts to the same thing.  Before any property can pass from your wife's estate to her beneficiaries, her creditors have to be paid off the top.