I commend your courage in trying. If you cant write the actual words, maybe you can take it slowly? Obviously this is an obstacle for you and one you apparently would like to get past.... why not just tell him that you have something that you have never told anyone and at some point may want to bring it to him? Sometimes, for me anyway, just acknowledging that there is something there and you may want to deal with it eventually can be enough to calm that storm inside PLUS it gives me the opportunity to discuss what I'm afraid of.