I personally don't think YABU, I don't know your circumstances anymore than what has been written in your thread, and you seem fair to me! Just wanted to tell you how we spent our Christmases as children of divorced parents...
Mum and dad used to alternate every year, so, if mum had us Christmas, dad would have us new year and then the following year we would switch. We used to stay at one parents place until mid afternoon on the 27th (my birthday, so I got to see both parents/step parents and half siblings as well), then we would be dropped off at the other parents house. We used to have 2 Christmas days, one with one parent on actual Christmas, and the other was usually "Christmas Eve" on the 28th and "Christmas Day" on the 29th. We LOVED it! We loved how special we felt that FC would make a special trip out to deliver our presents after the real Christmas Day, and we would celebrate just the same!
As adults, myself with a baby of my own and one on the way, and my brother with 3 children. Other brother grown up, and sister moved away, we still try get together and to alternate as best as we can, with the occasional new year spent with all of us and both parents and step parents together. I wouldn't change my childhood Christmases for anything! Just thought I'd give you another perspective... It also meant that every other year one of the parents could have a good drink on New Year's Eve and not have to worry about us!
Sorry for the mammoth post, just wanted to tell you about my own childhood experience. Pure magic!
FYI, my dad was a bit of a deadbeat- he left when youngest of us was only a couple of months. Sleeping with my mums best mate and he never paid a penny towards anything for us, quit working so CSA couldn't claim, and on the rare occasion (after years of getting nowhere) when he was asked to get school supplies, my grandparents ended up getting them for us instead. But, we saw him more than the courts said he was allowed, and had these lovely Christmases because my mum knew how much we all loved our dad.
I think your suggestion is admirable to split the day, he treated you horribly. I hope you come to some arrangement that suits all of you!