I hope I could accept it, also, though, like Luckylegs, I don't really know. I think it's very normal for you to hurt, Day6, but, like others, I'm sure it will get easier with time.
I'm glad you're wise enough to be letting go of the "Little House on the Prairie" fantasy. Maybe you shouldn't try so hard to bring them all together either. You're looking at this in terms of whether or not they want to be with you, but is it possible that they don't really enjoy each others' company? Some adult siblings just don't.
Also, how would you be any more - or less - of a "rock" for your older son because of a few miles difference? If you're a rock for him here, you'll be one for him when he's in London. If you're not, then you're not, no matter how close he lives. I'm sure you're a great source of support and encouragement to all your ac. But I think this "rock" thing is just idea you've created in your own mind. Now that ods is relocating, that idea has been turned on its head, but I'm sorry, it was probably never real. That hurts, too, I suppose and I'm sorry. But please take pride in the fact that ods can be independent and is most likely a rock for himself.
Your own experience shows you that a young person can go out on their own, be just fine, not give much thought to their mum, and yet still love and care about her very much. I'm sure that's how you ac feel about you.