I used to have this problem too. The way I did it I first would write it out . the first few times all I could get out on paper was r and over time it bacame the complete word then I wrote that word over and over and over until I was so used to seeing the word as I wrote it I started saying each letter as I wrote it. then as I did it so much I wrote it faster still saying each letter until finally about two months after starting it I was able to say the complete word. then I kept saying that word out loud every time I was alone. Then when I was used to that I added the sentence by doing the same process over again for the words I was raped. in a few weeks I could stand in front of my therapist and say the sentence without even a blush or quicken heartbeat.