I get called a fussy eater and I definitely was as a child but I don't think I am now. I will try anything and eat most things unless I already know I don't like them (e.g. loathe aniseed and coriander, but can manage coriander in strong curries if it's not the main flavour).
I accept that some people just cannot or will not face some foods for whatever reason. The problem I have is when it's an adult refusing to eat anything other than kids' food. This sounds like what OP's husband is doing.
We had a wedding guest who was like this. I was pretty stressed organising the whole thing mostly on my own whilst also doing a stressful job and a part-time degree, so was overreacting to lots of things anyway, but when I got this RSVP from this chap's wife, re her Fussy Eater H, I really lost it. We didn't send out a menu with the invitations, just asked people to say if they were veggie or had any allergies. This is what his wife said: "FEH requires a simple diet and would like to have haddock and chips (not chunky) for his meal. If not, plain chicken breast and potatoes (no bones or veg please)." WTAF. Sure, we'll get our venue with its rather niche style of catering to do something just for him, because after all, it's all about him... oh wait, no it isn't. Not like it was complicated cooking he was asking for, but the 'requires a simple diet' and 'no veg' and not chunky chips and 'haddock' as opposed to cod, cos heaven forbid they taste slightly different... He bloody well doesn't 'require' anything, he's just a 45yr old child! And if he doesn't like veg then just leave it on your bloody plate. Etc.
breathes
I did lose it ridiculously at poor DH even though he agreed with me. In the end we arranged for FEH to have 2 child's meals instead, which wasn't much hassle tbh but still annoyed me as we had to pay the price of the adult meal for 2 x portions of the kids' meal - chicken nuggets vs steak, not exactly the same price range.
Luckily DH thinks this couple (his friends) are more than a bit mental so we don't really see them often. We married a few years ago and I'm still not over it (obvious much?) so I don't think OP is being remotely U to complain about dealing with this every single day!