Hiya, I moved your thread into the hoofcare section. How about some pics? Without pics, general info only...
Chances are, a 1" 'chip' isn't likely to cause any issues, no big stress. Altho agree with apuetsot that I'd rasp the corners of the horn that's left, to reduce likelihood of them breaking away too.
Chances are tho, that if this happened & she's only 3 weeks out from a trim, that she may have been left too long in the first place, &/or she has seedy toe or weak hooves otherwise. Yes, constantly wet footing is likely to have an effect, softening the horn, but is not the cause.
Unfortunately the Keretex does absolutely nothing for keeping out excess moisture, and as it bonds the proteins, forming a hard, thin layer, can even just create a better environment for seedy to thrive. On top of that, if you've been putting it on long term, as in many weeks now, it can make that outer bonded layer brittle, so more likely to crack. So depending where you put it & how long, it may actually be doing more harm than good.
So... I'd quit the Keratex & instead start using an antiseptic to kill any shallow infections, and ask the farrier whether/how bad any seedy is & he can dig it out when he's next there, enabling you to get that topical into any deeper holes. I'd aim to keep her on dry footing, at least for a time after treatment, to let them dry & then the antiseptic soak in. You can also pack her feet with salt & wrap or boot, or soak them in a very saturated saline solution. That will help disinfect, but also draw out some extra moisture through osmosis.