My only advice is to write it out (it is OK to take suggestions at this point) but then sleep on it and the next day, read and evaluate it using your own judgement/feeling about how it sounds. While advice can be good, the final product has to be what you are comfortable with saying. When my H and I were in the USAF and I mentioned an issue I was having with someone--he would urge me to use this tactic or that but the way he dealt with people just didn't fit my personality so what worked for him didn't necessarily work for me. We come across effectively when we are authentic and sincere. But definitely say something--you matter and you will be valuing yourself by not letting this continue to slide. When you are angry, sleep on it at least one day! The sun will come out tomorrow!