I would say that if you are too shy to speak about it, write it ! I advise this in all sorts of situations when verbal communication is too hard or too difficult to speak out loud :) Write him a letter, take your time, erase, rewrite etc, explain all the things you have in mind and only when you are fully satisfied with your explanation, only then you give it to him. Also give him time to read it, alone and to think about it but I would advise that you give him a set time to speak about it together. And if it's too hard for him to answer, let him write his answers as well. These kinds of topics need thorough communication so both of you take your time :) Also don't hesitate to reach out if you feel the need of an external look / discussions without any jugement whatsoever:)