My Sister in Law Falsely accusing me of videographing her

I was happily married, up till now. I have been married for 6 years, blessed with a child 4 years back, lovely in laws everything going good. Up till 3 days back my youngest sister in law told my wife that I have been videographing her in a wrongful manner and sending her double meaning messages since a very long time. My history with the family is very old, older than the marriage. Their father passed away 10 years back. I was in a relationship with the eldest daughter since before that. After that my relationship with the family grew closer and closer (comprising of 2 sister in laws one 5 years younger and other 10 years younger and my mother in law). I did everything I could to support the family. Since the last 2 years my youngest sister in law (the one in question) has been into acting, and living away alone from the family. 3 days back when my wife received screen shots and messages and a call from my youngest sister in law she was in a state of shock. She shouted at me fought with me over it, and I was unable to understand what had actually happened. When I read the entire conversation and heard what she said to her on the phone even i went in shock of what had happened. It took me time to realize that every message I had send in a good way was taken in an opposite manner. I discussed it with my wife and she realized that there was nothing substantial in it and was just her (my sister in laws) perception towards things. I have always been inclined towards my in laws as both my sister in laws used to consider me more of a brother than anything else. I have picked both late at night from work, airport, railway station and where ever they said without question. My youngest sister in law(the one who raised issues) used to call me at odd times to pick her, give her money if and when she needed, took her shopping when she said but never with the wrong intentions. My wife told her mother the same night, and she was in a state of shock too. She scolded my wife for believing her sister and fighting with me. I spoke to my mother in law and told her not to talk to anyone about it, not even my sister in law who accused me as it will just spoil the family relations. My sister in law (in question) told about this to my younger cousins, taking them in confidence of not to tell me about it, which they did't. She has been visiting few psychatrist in the last few years, and told my wife its because of me she needed their help. Being scared of how the social media works and how easy it is to blame someone, I am scared that if she raises this issue again in front of friends, family (who already doubt her), on blogs or social media or any other manner, is there a way i can safe guard myself, like apply a restraining order or something of this sort, or maybe register a complaint somewhere to avoid further problems.