If your wife is not disabled, definitely put a time and amount limit on the spousal support. This is her decision; she will need to find a way to manage. You are already planning to take care of house and bills. Honestly, that is more than enough. I would say your obligation is more toward the kids and their education perhaps; otherwise, she will need to find a way to be on her own eventually - otherwise, you will end up financially tied to her with no end in sight. Should be contingent on her getting some retraining, education, etc. so she can become independent as soon as feasible.

My sister found herself in this situation (also Texas). 17 years of marriage - 2 teenagers. She didn't ask for the divorce in her case, but she had given up her education/career to basically support her husband through their marriage. It wasn't easy, but she went back to school, finished her degree that she had given up to get married, and is much better off in her independence. Her ex provided support for the kids - helped them through college, but she never got a dime in spousal support except for the kids when they lived at home.