Given your kids reaction and the way she treated you two weeks ago, I would have been cool at best. I would have answered the door, not let her in, thank her for the apology saying the kids should always come first and you would appreciate a scene like that never happening again. Then say you have to go have dinner with your family and closed the door firmly. It sounds like she could just be fishing for her brother. Of course, she could be really sorry, but she will have to prove to you her true intentions over time. Just showing up like that is rude.