Bless your heart.
It sounds to me like the biggest hurdle by far is the association of what you went through (which I am sorry ever happened to you

). That is something that can take much therapy specifically focused on that one area to correct.
Something that can help immediately though is trying to relax about the "O."

You know that O's don't come often for you, and you being stressed about it doesn't help whatsoever. I know and appreciate your husband's importance on your O, but you feeling...obligated, I suppose?...to have one for him isn't helping either one of you.
Try to explain to him that O's for you simply don't come often. Explain that it isn't his fault. Basically, try to alleviate the sense of him being "inadequate" (which of course isn't the case, but there's a sort of degree of pride and...lol almost duty...in making sure you're covered, so to speak

). By doing that, that can help you both out.
I hope things improve Big Mama, and I wish you all of my best.
Hugs,
Harley