Threat for legal action by company for not completing notice period

I was working in esens it solution pvt ltd.. I signed bond on 1 March 2016. After signing bond my boss was treating mr as a slave always abuse me, torture me and always Threat for terminate.. and not even gives salary on time. He always pay salary of 1 month delay, & if anybody asked for salary definitely he was ready to Terminate. some how I completed my 6 month of notice period their. On 1st October I gives him my printed registration but he won't accept that. And Threat me to black list in all software companies. I was very mentally depressed because of his behaviour. So I stop going to office.. But now after 2 months his Advocate send me letter and asking me to pay 50000 for not completing notice period.. My salary was 7000 and he not even pay for last month salary.. now how can I manage 50k.. please help he out, I m very depressed now.