No Harold. You're not thinking this through. You're not a lawyer so I don't expect you to understand the details of litigation. So let me explain in some more detail. The OP asked if the therapist could be forced to ADMIT that he took money fro to not provide the services the OP believes the therapist should have provided. An admission is a statement from a person affirming that some fact is true. So an admission would be something like the therapist stating "Yes, I took money from your ex in exchange for not providing those services." That admission could then be used against the therapist. But there is no way to force the therapist to make any such admission. In litigation you can ask for the admission in requests for admission, as part of interrogatories, or in a deposition. Absent a good claim of a Fifth Amendment privilege (which would be available if what the therapist did was a crime) the therapist can be forced to provide an answer. So he answers — and says no, he never took money from the ex in exchange for not providing the services. That may be true or it may be lie. But either way, once he's answered the OP would be done. He cannot force the therapist to say that he did take the money. He could not successfully go to court, stamp his feet, demand the court force the therapist to make that admission. So if what the OP really wants is the therapist to be forced to give that admission he's going to be disappointed because there is no way to force the therapist to do that. He can ask the question and hope for the best, but that's it.
Of course in litigation the OP could in discovery seek evidence like bank records to try to prove that the therapist did what OP alleges. But those bank records are not admissions by the therapist. The bank records would be admissible evidence, but would not be an admission by the therapist. There is a significant difference there between the term admissible as it relates to getting evidence before the court and the term admission which relates to statements made by someone. While the words are similar, the context in which the terms are used matter significantly. If the OP can get enough good evidence to build a case that the therapist did what he claims the therapist did then that would of course be useful to his case. But constructing that case does not result in any admission by the therapist that he did it. You see this all the time — most cases that are won are done without ever getting an actual admission (confession) that the defendant did what he was alleged to have done. Instead the plaintiff in a civil case or prosecutor in a criminal case has to prove the case without that admission using whatever evidence they have gathered.