My 2.5 yo DS is DE, as is the 17 week old fetus I'm currently growing. They may not be mine genetically, but I am their biological mom and I couldn't imagine loving a child any more than I do. We have the books ready to start having conversations about DE, but DS is too young, too busy, and has too much energy to even contemplate such complicated issues right now. All he knows is that I am his mommy, and for now, that's enough, though I eventually want the story of his conception to be a natural part of who he is. I know there will be difficult conversations to come in the future, but I hope the strength of our relationship will help weather any storms.
This board is a constant source of resources, as is the Donor Conception Network. There, you can not only connect with other DE parents, but find links to books, literature, videos, and all sorts of useful information.