Dilating or having intercourse in water simply requires a different type of lube. Water based lubes won’t go very far. The vaginal dryness noted for about four months, related to the Botox injections, interferes with natural let down. It is for this reason I recommend using cocoa butter, both on the outside as well as on the inside, and on your dilator or partner’s penis.
I especially recommend this to women using a hot tub whether or not they have vaginismus. The bromine in a hot tub can be very drying, and pre-treatment before hot tubbing can be protective. For those who stay a longer duration simply re-apply every hour or so. Other lubes to consider are silicone based and olive oil or any of the other natural oils.