Such a big first to get through, Kim, but get through you will because you have to even though it's so, so hard.

And as for so many other twins, life really does have this habit of twisting the knife it stuck in your back. When my son started pre-school a fews months ago, who were the first 2 children we met? Twin boys born 4 days earlier. (I cheered, honestly I did, when we got a notice recently about next year's class being split into 2 and the twins being in a different class.) We had our first foreign holiday recently staying at the same place as two other families, and of course one of them had twins (mixed this time.)
I, too, find it very hard to live without my little boy, getting through all these milestones without him, and I hope it's a small comfort that other people know just how you feel.
Take care.