Kindly, gently, factually vs. emotionally only, usually in writing along with verbal follow-up once they've had time to read and digest it, (or else I'd surely leave stuff out, trip over my own thoughts, end up getting even more emotionally charged, etc.), being sure to not let myself just ignore it once I share it, or chicken out, as I so often used to do.
I make it a point to ask him how my responses/reactions to certain things effect him rather than just assuming, as he's not one to openly share much without me going first or directly asking. I, on the other hand, very openly share feelings on a regular basis, if not verbally, there's definitely no hiding my facial expressions, even if I wanted to.
His responses have been overall very supportive, minus a few bumps in the road, although he still struggles with wrapping his head around believing another person could/would treat someone in the ways I was treated, wondering how the hell I lived through it all, and sometimes struggles with how some things can linger in ones psyche for so long and wreak so much havoc, and I think he feels a bit frustrated in not being able to fix it and make it all better.
I hope he never has a reason to be able to fully grasp any of those experiences up close and personal as I did. I had to break it down for him in some not so kind verbal ways a few times when I was really struggling with some major stuff and wasn't feeling heard...always followed up with more educational info to try to heighten his awareness vs. criticizing his responses and reactions...and he eventually seemed to grasp just how important compassion and presence is and no longer demonstrated a mindset of expecting it all to be "fixed" and tucked away for good.