I wanted a shower downstairs (we don't have one in the house). He set up a showroom visit.
At this point, he sounds supportive.
He said I could have total say and he would look after the kids.
Again, this all sounds great. Although there's no reason you can't both have your say really.
I say I'd like a bigger shower head than the standard one. His response 'that's massive, it's like the width of the cubicle. No the one we have is fine
It's okay for him to give his opinion too. He may just have been surprised at the giant shower head! But I agree with @GingerIsBest you could have said, "Nope, you said that I get to make all the decisions and I want the bigger one."
When we got out I said it was a bit pointless as there wasn't really a choice, we got the one cubicle they have.
What was pointless exactly? Did you get a shower or not? I don't understand this.
He exploded and said I was impossible, that I had total say and was never happy.
Exploding sounds OTT. Did you get your shower with the larger shower head then? If you did, you got what you wanted and should be happy. If you didn't, you refer back to the fact that you were supposed to have total say.
I said he vetoed the big shower, he said at no point was that the case.
I have sometimes thought my DH was vetoing something, but sometimes he points out why a floor covering may be impractical. I admit I am completely impractical. I take his comments to heart, then don't do what I want, then get pissed off. We talked it out once and he said he would totally do what I wanted if it was very important to my happiness, but that he feels he should point out pitfalls he thinks may be important. He doesn't mean I shouldn't still go ahead.
I am not saying that's what has happened in your case. I don't see any pitfall in having a bigger shower head. I'd have taken him at his word and said "Well, it IS big but I just love it...it'll save time getting wet...thanks for giving me total say!"