I've written quite a few times regarding what constitutes the crime of 'prostitution' under Texas law. One of those threads is stickied at the top of this forum. You might read it to better understand what the state has to prove for you to be found guilty of prostitution. From the facts you give, I don't think you can be because you didn't make an offer to engage in sex for money.
Also, from a practical standpoint, I think it's highly unlikely that the police will go to all the trouble to make a case against you based on emails, especially when it would probably be very difficult to prove the emails are authentic and that you wrote them. It's just not a real-world scenario to think the cops in New Braunfels (where there is much more of a laissez-faire philosophy than in other parts of Texas) would send a SWAT team out on a Class B misdemeanor without a complaining witness. Sure, cops make busts for prostitution every day, but nearly all of them are for street activity or the result of undercover stings.
Finally, you might read this thread:
"Can a review be used as evidence in a prostitution case?"
The analysis in that thread isn't EXACTLY on point, but most of it is.