Come on. You know the answer. Namely, you have to ... simply... stop.
Tell her, no. No texting. Period.
You're asking for more tools? What, because you think you'll outsmart the first set of tools? Well, yes you can. You're smart enough to outsmart 100 sets of tools. Are you asking for 101? I think, no.
But since you're maybe asking, I guess I could venture one thought. Are you willing to give up all texting? That might be the only way to stop this texting. I don't know if other carriers are the same, but Sprint will cut off texting on demand. Account changes require the six digit pin. If you give your current pin to the filter gabbai, perhaps he can change your pin to something you won't know. bingo, no more texting.
Of course, you'll be smart enough to undo this one, too, if you want to. Just call in and say lost PIN and provide all your personal info, etc. So who's gonna be your accountability partner or whatever? Come on, you know yourself better than anybody -- just ask yourself, what's it gonna take to make it stick.
Unless of course you're trying to tell us that sexting a single woman is a good thing....
Okay, fine, there's your tough love; what am I missing about your story that changes this view?