Employer made me serve the notice period without my intention, advisde

I have been working with a college as Director for last 8 years. Recently on Nov. 25, I had a job offer and accordingly I mailed my resignation to the college. But the management discussed the matter with me on one to one basis and convinced me to stay with the college. They did not responded to my mail. But to my surprise, i received a mail on Jan 24th, 2017 stating that my Resignation has been accepted by the college and for this purpose my notice period has been counted from Nov. 25th, 2016. And i have been suddenly asked to relieve. So kindly advice whats my position in this case and can employer legally justified in counting my Notice period from back date.