Required Legal advice

I have developed a school management ERP and E-Learning software which I have copyrighted as “Campus Management Solution ERP Suite with Community Digital Library” vide No. 13146/2012 ( Reg No.SW-6990/2013 of Register of Copy Rights, Govt. Of India.) I have started marketing this product from 2010 and had got about 6 customers . On my health ground, I was in search of Marketing partner, during which I had met one Person in Hyderabad & he had agreed to do marketing on royalty basis with 40 percent on invoice. I have all the mail conversations between me and that person from 2011 on wards about Product. He intentionally, avoided making an agreement and orally said he will make the agreement on the same after 6 months of test marketing. He asked me to join in his Company to look after the given ERP. So i got Appointment letter on 1st August 2012 & joined in the Company on 3rd Sep 2012. He keep postponed agreement, so I have applied Copy right on 25th Sep 2012 and accordingly got copy right. In that they mentioned my product published year was 2011. I gave them Developer code which contains Secured Libraries which can't be break. He is running my software product on other name from his Binami Company which bear 2 different Directors which is no way relevant in our discussions. After that he had kept dragging on the marketing, got 200 plus customers and is generating Rs 6 Lakhs revenue per month, but never paid even a single penny of royalty as committed. He multiple times had tried to get hold of the copyright from me, which I had kept on rejecting and asked to make the marketing agreement as discussed earlier. Now, with the bad intention of cheating on me, is trying to sell the product to other parties, claiming him as the owner of the product. In Appointment Letter there is one clause saying "While employed with the Company, you will promptly disclose to it and Assign to it your interest in any invention, improvement or Discovery made or Conceived by you either alone or jointly with others which arises out of any proceedings relating to such invention improvement or discovery and in obtaining domestic and foreign patient or other protection covering the same" Showing the above clause he is saying my product is automatically transferred to him with the Employment. I have all the mail proof that he has taken & marketing & also i have Copy right . Even Police dept is not booking FIR on the above Clouse. What are the grounds i can fight. Is Appointment Letter valid? Rama