Eviction Process

I am not a landlord, but a tenant seeking some advice from experienced landlords. My husband and I are renting a duplex in a townhouse. The townhouse has 2 duplex apartments and an additional space about the size of a studio that has a nice sized backyard. We occupy the largest duplex and another couple rent the second duplex. Both I and the other couple renting the 2nd duplex are all hard working professionals and get along great.
The application process for our places was rather strenuous (background check, w2 forms, paystubs, bank accounts with a minimum of 6 months rent cash in each account, as well as the standard credit check and income requirement). Although a bit much in my opinion, I did not mind too much because I knew this meant the LL wouldnt just let any old body rent the other portions of the townhouse. Boy was I wrong.

There is a tenant living in the studio who is an absolute nightmare. Without drawing this out too much, they curse, scream, and fight daily, and leave garbage outside on the yard(sometimes with maggots, yes maggots squirming through their bags). The police have been called multiple times by neighbors and going/being home is an unpleasant experience. As we sit down to dinner all we hear is you sick fuck, you goddamn dick, fuck you bitch, suck a dick and this is by THE CHILDREN, the adults are worse!! My 9 year old daughter is right there to hear all of this and even she is starting to feel uneasy. I dont even want guests over because I never know what will occur day-to-day and I worry about our safety (there is a door in their place that walks right into our place, it is locked but in all honesty it wouldnt be that difficult to break by a determined individual). There are 5 people living in the studio and 2 more people moved in last night (making 4 children and 3 adults in A STUDIO). They are not paying rent and have not done so in over a month, and we have only lived there for three months.

The landlord told them he wants them out last week and they told him they are not going anywhere and they havent. We have a laundry room and a garage which the landlord locked Saturday to keep them from using the washer and dryer, but he gave myself and the other duplex tenant keys. I went home last night to find the tenant that did not have a key broke into the garage area to do her laundry!! To make matters worse, she must have had dozens of bags because she literally did laundry from 4:30 (maybe earlier but that is the time I got in from work, until at least 11:00 (the time I went to bed), I know because I couldnt do my own laundry, which is still sitting in a bag.

We like the place (it really is a nice place) and the landlord is a really nice guy, and we have already put so much time, money, and effort into moving, but I dont know how much more of this I can take. What I am here to find out is for anyone who has gone through the eviction process, how long could this take? I can be patient for another couple of months, but a year or more of this is too much.

We are in NYC, the studio apartment in not legal, and my LL rented to a single male (or so he thought) and there are currently 7 people living there (which they flat out lied about when the landlord asked), they broke into the garage when he attempted to restrict access (this was yesterday). They man did not go through the intense application process we went through because the apartment is illegal and he seemed like a nice guy, that man by the way has not been around in two weeks. The people staying there now are his ex wife and her 3 children, and another couple and their child).