Serving Notice Period

My case is a lil weird, so i joined a startup and the CEO offered me a job with a good hike and initially without much thinking i did join, now post joining the founder/ceo was too snobby and was getting on nerves with huge harassment commenting on performance and work beyond office hours in just 10 days of joining, however i continued for 45 days t get my one month salary as he used to pay very late every month, also he didn't offer an employee job to save taxes and instead asked me to get on a consulting agreement as a consultant which was basically a employee job agreement framed in a consulting agreement, now there was no probation period or nothing mentioned but a 3 month notice on my end was mentioned or relevant compensation, now after 45 days i just left due to some family crisis and another job opportunity, now the employer has sent me a notice to pay him for 2 months and 15 days as per the notice period... which i dont want to pay.... i want to know what should be my next steps also just after working for one month and getting a salary for one month can the court give a verdict to pay back for 2.15 months? One more thing to add he sent me the notice on a wrong address where i dont stay anymore and came to know via few the notice is not delivered yet, so if i dont get the notice am i liable to reply to the notice?