Ex contacts me with details about me?

His ex recently got in touch with me to let me known they kept seeing each other. Thus finished with him. However while chatting with this ex (not so ex obviously...from her point of view i am the lover) I realised she knew very many details of what we did when we were at his house..."i know when you got to the spare room you found the book on the table"..."i know when the amazon mail arrived on Saturday night you asked why amazon delivers at night...they were my parcels for him". She also knew my texts to him etc. That I can understand...she might have got into his phone and checked. But how would she know what I did or said? I am worried she might have planted cameras in the house and videos of me might circulate. What should I do? Ps. Known the Jerk only a couple of months so not too bothered and glad to be out but freaks me out that she'd know these details. Any advice what to do? Should I go to the police? I sent him a message to ask but doubt I'll get an answer.