I'm guessing he tells my this other woman that he's divorced/separated from you. Most women who know they are the other woman don't want to see the kids because they know the kids will tell their mom, and they most certainly aren't giving the kids Christmas presents! He's using you and lying to you, just as he's using her and lying to her. If you know who she is, you might want to inform her about how he really is.....of course after you kick him out and change the locks. And if she takes his side and defends him, she's a skank who deserves an @sshole like him!