How do I deal with a narcissistic In-law?

Study about narcissm, that is crucial. With regards to dealing with them, keep little or (if at all possible) no contact with them, if they're unwilling to rectify themselves and are bringing just chaos to your life.

My Father in law was a wolf in sheeps clothing and it wasn't until my husband himself saw the toxic behaviour/ manipulation and ultimately his inappropriate behaviour around our children that we cut him off completely. I would say help your spouse to open their eyes but let them take the lead as to not cause a rift in your relationship. There is a lot of resentment on that side of the family now but we don't have to worry about dealing with a narcissist or someone who could hurt my children! My advice is to set healthy boundries and continue to do this until you are comfortable.