My ex actually texted my daughters during a mediation session with lawyers saying "daddy's not giving me enough money".
Did your daughters tell you what she texted or was that what your stbEx claimed? As has sometimes been commented here, to quote one member, "I know when my ex is lying, it's when my ex opens his/her mouth."
Are your daughters taking sides and influenced overmuch by their mother... or perhaps are they just trying to stay out of the middle of the conflict? Their mother is of course trying to guilt you into appeasing her, and using the children as weapons.
Unless there is some legal reason to involve them in documentation or involvement, you wish to express to them some gentle thoughts. "I understand you don't want to be drawn into the divorce details. I am happy for you both to choose to let your mother and me work it out between ourselves. Be assured that the court and lawyers have laws and procedures to ensure both parents have protections and safeguards for each to have a reasonable outcome. This divorce was unavoidable and certainly not your fault nor your responsibility. You know me, I'm still the same person you've always loved all these years. I welcome our contact and trust to be as before."
It's possible that once the divorce is final the children may resume communication and relationships.