Monbon, yanbu, I don't think. I certainly think your dh dismantling the cot was being very unreasonable.
However I do think you need to discuss it together as adults.
BE has a great idea; "one suggestion could be to tell DH, he has to do all the night wakenings. i.e. Fetch the baby from the other room to your room for you to nurse her and he need to take her back to the other room and resettle her. I doubt he will agree to it wink and even if he did agree, one night of actually doing it, will have him bringing the cot straight back to your room."
This is exactly what I did with my dh. And it worked. After just one night of this he agreed with me that it was far better that ds sleeps with me while he still feeds in the night. Dh sometimes co-sleeps with me and ds, and sometimes in the spare room (if he has to be up early the next day, or if he has a big meeting or something).
The way I see it, dh and I had eight years of sharing a bed together. And we will have many, many years in the future. So a year or even two out of that bed sharing arrangement is not that much, really.
Another way to think of it is to ask your dh to put himself in your dd's shoes bootees. If he, a grown man, wants to sleep with someone else in the bed, how much more would a six month old baby?
(Also sex can be better if it is not relegated to a last thing at night while you're half asleep thing!)