I am a practicing attorney in Texas. Under Texas law, her lawsuit was timely because Texas law provides for child support after the child turns 18, if that child is still in school. Essentially, she waited until the very last possible moment to file this suit and it still be timely.
HOWEVER: If you have proof that you have been supporting your daughter, this can be used to offset whatever amount she's requesting. It is vital that you respond to the suit and request that you be notified of any and all hearings, or else they can and will default you and you will be saddled with back child support without your consent.
The language requesting attorney's fees is standard to Texas pleadings. Rarely does a Judge grant it. In this situation, where she waited until the last possible moment, I think a Judge will likely see this as an attempt to grab money, as opposed to an action brought out of real need.
A Judge cannot order you to pay for a specific college. Texas does not require parents to pay for their children's college education UNLESS your divorce decree provides for that.
It is worth it to hire an attorney. You don't necessarily have to hire an expensive attorney, just one who knows what they're doing in the area of child support litigation.
Texas allows for retroactive support back to when you separated from the mother, so if you hypothetically separated from the mother 10 years ago, you could, if you had no proof of support, be ordered to pay 10 years worth of support. Support would be ordered based on what you make now, and how many other children you support.
Hopefully by this point you see why it will be necessary to hire an attorney, especially if you are out of state and are unfamiliar with Texas child support laws. To put it bluntly, Texas still very much favors the custodial parent
when it comes to child support issues, so it is important to act on this quickly.
www.texaslawhelp.org has some information on Texas laws in this area, and I'd suggest reading over it before you speak with an attorney.