Termination from the Services

Hello All, Greetings of the Day!!! I was employed by a Hyderabad based Software Services Company from Apr 2017 & recently 3 months back I got good annual hike. As per the normal terms & conditions of the contract, we are not supposed to join the customers/ targeted customers of the company. In the month of April 18 I was approached by our competitor and I went for a lunch with them to discuss the opportunity, as it is very common in the IT industry. They were willing to release the offer in the first week of May which I refused. Now on 2 Jul, HR called me and asked me my plan for continuation with the firm as they came to know that I am actively looking for a job. I told them that I m willing to continue as I am comfortable here. Same day, The CEO & HR Head called me and told that they came to know about my interview with the competitor and they want to terminate me immediately as it a violation of code of conduct. I was escorted out of the office that time only. Now the same HR to cover up and create their impression are telling everyone that I have shared information with the competitor (they have proofs for it). I have 15+ years of experience and understand the value of information which I have to share. Please suggest me if I am wrong or if the Company is wrong, how to challenge the termination and ask for my right. Thanks in Advance Regards Dhiraj