Issued Fake Experience & Relieving Letter & Backmailing me..

Dear Sir., I am XXX, I Did my B.E with Great difficulty , After that I didn’t get any job,, Then Did PCB Course , And started searching job, I got a job In a company Near Peenya(Bangalore) They said , They gona train me for 6-month ( I needed to work for free), Then Depending on my performance they make fully time employee with 1-year agreement. ( Started my career from free-8k-12k-16k ).. After 3-month , I got Seat for M.Tech (DEC) , My dad is retired employee, So I requested my Company to allow me for Doing M.tech & I will Do night shift Job..( They said Okey- I worked for 1.5 years).. After My M.Tech , I got a offer for New Job in X-Company., ( Owner of company was HAL-ADA-Employee- Who was indirect partner and Real owner-Who is running company for 10+ years with out knowing Govt HAL-ADA & Do Products for HAL-Defence) I worked there for ~2.7 Years , It was 4-employee company( HR, Me, Mech. Eng, H/W Eng ) and Owner was a Hal-Employee ( Who is in service ) and Another.. I use to Work Hard use to do 3-4 ppl job like( Doing Tech. Tender, CDR, PDR , Doc. Presentation, Designing Hardware all …( All was good , I got salary from 16k-18k-22k-26k ) But, Problems came when I got Better job in Y-Company (MNC)on 16th-Oct-17 , In my X-company I Applied for resignation on 14th–Sep-17 , They didn’t agree , They said, He give same salary and we give you better Position etc., I disagree all this , So they were anger and didn’t agree my Resignation ., They started Blackmailing me, Telling you needed to give 2-month salary for relieving .I said I will serve one month and pay one-month salary( Which they said to pay by cash – I paid it) After that on 5th-Oct they gave Expi. & Relieving letter ( In that they written subjected to Completion of project ) , Then I took help of my dad and went to my X-Company and Requested to Give letter properly, They said give me one more month Salary money then they will give properly .. Then we paid it by cask – As they requested for cash only .. Then they gave Expi & Relieving letter with different sign- I didn’t notice it,, That Experience & Relieving letter I submitted to my New ( Y-Company ) , Then after a week , Y-Company asked my X-Company for Background verification they said, Sign in those letter is fake, So Y-company HR Called me , I explained all this, But she didn’t believe me , So I said her, Give me a chance I shall ask to them a get new Letters from them, I went and took it and gave to HR., HR said Okey.. But our company said, it’s a black-mark on X-Company , You accept and write a letter telling 2nd Expi & Relieving letter is Fault and I have done Cheating making it fake, They forcefully wrote a letter from me, Telling if you don’t write and give , We will not issue New Expi & Relieving letter., Now, Keeping it they are telling Come Back to X-Company or we will spoil your career … Plz help me, What I Can do..