Until you have something that will stand up in court - physician reports, therapy reports all you can do is like your therapist says watch her behavior patterns and so on and any changes from what you normally experience with her then get the documentation and so on.

regardless of past abuse if anything is going on there will be noticable changes.

one thing you may want to keep in mind - being abused yourself there is a possibility of you seeing problems where there arent any because the child could be the age of an abuse situation that happened to you and so on,

So if you suspect anything may be going on then its time not talk to the child about it but contact a professional - physician and therapy professional and let them know what you are seeing in the child and let them take it from there. They are spcecifically trained in finding out if a child is being abused and talking to the child without scaring the child and or seeing symptoms because of their own abuse history. and here in the USA those professionals are mandated reporters.

If something is happening and visitation gets stopped, and the granparents take you to court to get their legal "Grandparents Rights" you have the documentation needed so that the court will not force you to give them visitation based on grandparents rights laws.