HOw 2 turn Off da tApe?

Something I have come to realise over a period of time is that I have a very negative tape the runs in my mind continuously. I have this negative self image that I project on others. Maybe it is my way of keeping my ego in check...I don't know. What I do know is that I need to learn to turn it off. The things I repeat to myself in my mind are like poison and I allow these thoughts to arrest any good thing I could be doing. I brow beat myself into lethargy and discontent. Those who are closest to me say that I am too hard on myself and subsequently, others. I don't know what this means. I don't know what it is that I do. I am so used to this way of thinking that I don't know any other way. It is making me cynical and I don't want that.