In fact she is not accusing you of anything illegal at all - you are as entitled to have your husband's funds in your account - even though you do not.
She will not stop saying these things simple because they are not true - quite possibly because she cannot imagine any woman preferring to be financially independent since it is not something she aspires to.
You have been through a bruising court process but at the end of the day your husband achieved the result he needed
( I will be very honest - had I been acting for him I would have made it clear that disclosure of the source of your money was essential at an early stage - not to shut his ex up but to ensure that her solicitors understood she was not telling the truth)
There is no need for there to be anything other than a minimum of contact between your husband and his ex since the nanny deals with much of the care of the children.
His ex needs to be told that he will not respond to any emails regarding you - and that in the event that she attempts to contact you directly then the police will be called - and it is important that you actually do this if need be
I do appreciate that this is not the answer that you were hoping for - but sadly it is the only one that can be given - you cannot change the minds of the ignorant who prefer to believe lies than truth!
Please ask if you need further details