If the therapist really feels this, they should have reported this to CPS. Has CPS contacted you? If so you may want to talk to the case worker. CPS can take custody of the child and place him with you while they are completing their investigation. Risky though. If CPS doesn't have a good idea where the abuse came from, they may place him in a foster home.
Bad news all the way around. But you have to do what you can to protect your child. See if the therpist is willing to write a statement and talk to an attorney. The attorney will help get the statement into a form that can be filed in court.