Suit over illegal occupation of 30 years

I have been sent a mail by a lawyer that I am being sued for my illegal occupation of a land measuring less than 70 sqm, and that a temporary injunction order has been passed by an executive magistrate asking me to not initiate any construction activities until next orders. The said land has been occupied by me and my family for over 30 years now, and I also built a "pucca" house in 2016. A person, claiming to be the legal heir of the original owner, has now come forward to claim occupation of the said land. My financial means to make an offer of out-of-court settlement is severely limited, and my ability to prove my 30 years of occupation, albeit illegal, is also not very encouraging. I had a telephone connection for some years in the early 2000s, and have an electric connection from 2008. The bills are also not well kept and I bet most of them are missing. That said, what are my options to restrict the suit from going in plaintiff's favor. My place of residence is in West Bengal, and I know that it has many legislations that actually favor illegal occupants or tenants who have been occupying the property over a long time. As you can imagine, my only strong point of contention is my long occupancy, so please advise if there are any such rules that legitimize my claim of land. I bet most of the respected lawyers here find a suit like this all the more often. So, please advise me what on actually turns up out of such suits. Is it more often that the plaintiffs get a favorable judgement?