My wife gave birth to a (biracial)baby that clearly isn't mine, and I'm divorcing her. But I'm worried about the relationship between my two kids and their new half-sister.

A month ago, my wife gave birth to a biracial baby girl. We're both white, so she was forced to admit that the baby wasn't mine. She's admitted to having an affair with a colleague of hers who is also in Medicine (my wife is a resident, and his job is something like "medical research assistant"). She says that she ended the affair, but that she wants to raise the child "and would still love her even if I left". I've already filed for divorce.<br><br>We have two children, a girl and a boy, aged 6 and 9. Obviously, I love them more than anything. My wife loves them to death as well, and she's a great mother. That's why I'm worried about the effect that this split will have on them, especially since their new sibling won't be "one of them" due to the inevitable "looks" and social issues that come with being mixed race. So far, my kids don't know about any of this, and my wife is still taking care of all three, mostly because I don't have the money to hire a babysitter and she doesn't either; she needs to go back to work anyways, as we can't survive on just my income.<br><br>I plan on getting sole custody of my two children, but I know that this will cause a massive burden on me, as I have a mediocre job at best and I know that my wife earns much more than me. Money will be tight for a while, and I'm afraid of what this will do to my relationship with my kids. They're still small and somewhat unaware of the world, but I know that this will inevitably create a rift between us at some point in the future. The affair also made me lose a lot of respect for my wife, which makes our conversations even more difficult.<br><br>I know this is somewhat /c/AmItheAsshole material, but I want advice rather than a judgment.