Land dispute with my neighbour

We have land dispute with my neighbout let explain our situation like a story My grandfather possession over our certain land (example 10.5 m)for nearly more than 60 years but as per patta(land record) govt has given my 5.5 m now what is the issue is that we mistakenly constructed house on my neighbour.but we constructed based on per my grandfather possession over land and also that house was also built by my neighbour(he was a constructor)during measurement of land for construction of house he not said anything about land but after 10 years now he fighting with us by citing their land record