In-laws instigating wife to leave me and escape with my child

This is my second marriage. I am 33 years old, have a married brother who is settled in his place and I have my own house and agricultural property. I am a governmental employee. I have a son who is 8 months old currently. My wife comes from an economically very disadvantaged background. My father-in-law is retired (doesn't earn pension), My mother-in-law and brother-in-law (unemployed) often seek help from me, and they have gotten increasingly demanding over time. Whenever I am unable to help, they immediately start meddling in my internal family affairs, they even abuse me, my father (my mother is dead) and instigate my wife to take my kid away from me. They even suggested that I abandon my own father. And my wife is sometimes victim to their constant instigation. When she is with me, there is no real problem. She doesn't have to cook, clean, wash, etc. She only takes care of my baby. Recently we have discussed that we must not let the in-laws meddle in our family affair again. HELP!