This is an extremely tricky situation in regard to having charges filed against you. Technically you are both considered a child under the Texas Family Code but you are considered an adult at 17 under the Texas Penal Code. Having sex, even consensual sex, with a 16 year old can certainly prompt an investigation if a complaint is filed. In Texas, there is an affirmative defense if you are within three years in age to each other (a 19 year old having sex with a 16 year old) but that is a defense.
The best advice I can give you is to contact a local criminal defense attorney to protect you from having to face a criminal investigation and potential charges. The last thing you want on your criminal record is a sexual assault even if you eventually get those charges dropped.
Technically, charges could be filed on you but, as the other answer stated, there is a defense to the charge in your situation since you are so close in age. The odds of charges actually getting filed are extremely low.
Obviously, this happens all the time (17 year old and 16 year old having sex). But, legally the 16 year old lacks the ability to consent and therefore charges could be filed. But because they are within 3 years age difference of eachother, they 17 year old boy will have an affirmative defense to any prosecution. Because of this affirmative defense, it is unlikely that the DA's office will file charges in this case. If contacted by a police agency, he should contact an attorney. He should also stop all communication with her and assume her emails and texts are being review by the parents and could end up as evidence. Good Luck.