How Can I Emotionally Manage The Stress And Manipulation From My Partner Who Uses Our Son To Manipulate And Undermine Me?

Hello Doctor , My estranged wife is too manipulative and has ulterior motives . We are separated for 5 years now and I have a 5 year old son who was taken away by her and her family members without my consent . I have been putting every effort to try to get closer to my son, but the lady creates friction in a mischievous way the moment she senses some closeness between us. This effects my day to day work to an extent . I have tried to use mediation , but that has not helped much till now . Mainly she is targeting money and using my son as weapon to emotionally drain me . for e.g a 5 year old says I will talk to you when you take me to foreign country (he doesn t even know what foreign means). When I tried to talk through this topic she casually ignored it as if it was his on words . My question is : 1) How can I emotionally control myself . Given my soft nature she takes that to her advantage to show her dominance , and I do not react because provoking her will only hamper my chances to talk to my son . so, what is the logical way to deal from a psychologist perspective .