I can very much relate.
I have felt vulnerable and scared when trying to tell my wonderful patient man about my mental health challenges. I felt like I was going to be attacked, that I was bad, that I was guilty, and other such painful emotions.
What works for me is that I give myself plenty of time. I take things slow and learn each step of the way. If something doesn't work I try to not beat myself up and I eventually move on, try something else.
Maybe you can find some playfullness even in all this - what if you text messaged him some of what you want?

Really though, it would be fine to try that, might work well.
Writing things down in a note form would be fine too.
Time and practice helps a lot.