I wnt through a very disruptive marriage break up, to the point where my ex wife even accused me of abusing our daughter, of course this was proven to be unfounded, but mud sticks as they say, and I even went through the process of supervised visits with my my children, do I have a case of defamation of character??

Did she make the accusation in Court?

Generally, you have to prove you suffered damages. If the charges were proven unfounded and the supervised visits have ended there doesn't seem to be much in the way of damages.

On the other hand, you seem to have a very strong case to prove the defamation. So consult an attorney/solicitor on the viability of going to court.

What is said in Court is cloaked by Law and cannot be used in a lawsuit.