Mental Torture

My Brother got married in January 2020 and we are only 4 in our home , Dad ,Mom, Brother and me. We are from Bangalore but married my brother to Tamilnadu girl from a village thinking that she will be supportive as village people have pure heart. My parents brother sister kept her showering with gifts , trips and everything one could imagine , our relatives told we should be patient and should not do this in early stage but my dad didn't care , he would give her mobile, Tv , Anything she would wish for .. All of a sudden she stared tortured my brother saying that you never ask my parents , and she started to say people that we don't have food in our home , my mom is torturing her , She don't want to come back and she wants separation and divorce and when we called all the relatives and showed she and her mother said we never did that.. And she just made a prank because everyone have seen my parents from past 35 years . The always lie , lie and lie we don't even remember when she last said any truth ..We want to make any kind of agreement and be safe because my dad is 70and my mom is 55 I can't see them suffer in old age ... And bride belongs to my mom's far relation she only married my brother to her and today she is saying lies about her . Please help