I Want To Move In, Tenant Wont Leave And Is Illegally Subleasing

I am a landlord in New England, I own a single family house that I rent to a tenant on a month-to-month lease. I want to move out of my house and make my primary residence the current rental house. I need to move for personal family reasons. For clarity, I intend to never use this house for a rental property ever again. It will hopefully be my forever home.

I had my lawyer send a two month notice (60 days) to vacate the property so that I can move in. The tenant is going insane because I was renting to him for far below market value (nearly half compared to other rentals around here!). He is trying everything he can to stop me from moving in. He got a lawyer and is trying to argue that I am harassing him. In his defense, I have been over to the property a lot taking measurements and seeing what needs to be fixed and/or updated. For example, I needed to check if the propane tank was low since I pay that bill and I don't want the pipes to freeze. During that trip to check the propane tank, the tenant called the cops on me, stating that me being over there is harassment. Needless to say, I am now keeping my distance.

Just to add to this, I recently found out the tenant is not even living there! Turns out he owns a house, and has been subleasing the property to his friends. These are strangers I have never met who have a baby and a dog in there. And yes, pets are against the lease terms.

I am under the assumption the tenant will do anything, and I mean ANYTHING, to screw me over or delay me moving in. He has expressed to me that this conflict has become personal for him. After the 60 day notice, what will happen? Do I have to take him to court? Do I have to go through the whole eviction process? How many more months are we looking at? What if after the eviction process he refuses to get out (or rather his friends he is sublease to refuse)? If he really wants to screw me over, how long can he drag this out using any and all means possible, legal or illegal? Also, since I now know he has his own house that he lives in, an eviction on his record has no consequences for him. He doesn't care about an eviction hurting his chances to rent, because he is actually not a renter.