What would you do in my situation - christmas arrangements

I really need help from a fair, logistical point of view on this. I have a 2 year old toddler, me and his dad split when he was 3 months old due to his dad cheating on me whilst pregnant/ postpartum and then left me for the other woman. He now lives in Wales and I live in England. He sees our toddler fortnightly on the weekend, he travels on the train as doesn't drive. I've always been so fair with everything, always remembering I love my son more than I hate his dad. E.g. I let him have him on mother's day and on his 2nd birthday, however last year I had our son through the 3 main Christmas days (it was the first one we'd had that we'd been split). We were having mediation at the time and he said I could have our boy throughout this time and didn't seem fussed. Also he was only 14 months so didn't really understand it last year anyway. This year I plan to have him but he wants him too. I said I'd be happy for his dad to have him on Christmas eve and Christmas day as long as I could have him on boxing day.. however due to the logistics of the distsnce etc it doesn't work as he'd never be able to return him on the morning of boxing day (trains don't run and even if they did its 4 hr journey). I don't know what else to do. He therefore says he'd have to have him all three of the main Christmas days and then alternate each year. I can't face the thought of not having him for at least one of the days, whether that be Christmas eve, Christmas day itself or boxing day. None of this was my choice, it feels so unfair, yet I try and put my feelings on this aside, yet I can't quite swallow the fact of not being with him for the whole of Xmas. He's now proposing that I have him this year and he has him the whole of next years Christmas but I just think I'd be sad all year thinking about that. I could ask my family to do an alternative date but then feel bad for them that they're having to do that and also they wouldn't open their presents I guess my son would just open his as it'd be like a week before real Christmas. How do I navigate this? Do I suck this up? How do others deal with this? Next year he'd be 3 and really understand it, if he were to spend the whole time with his dad I'm scared he'd be upset with me or not understand where mummy was at Christmas. It's breaking my heart