You needed to go see a lawyer yesterday. You absolutely must, MUST go see one. Before you talk to your wife about anything, you need to know where you stand. If you don't you will make mistakes.
Now, your wife is correct about one thing: your daughter absolutely needs to go see a counselor. She needs someone to talk to - someone who is not her mom and dad. She's hurting, and whether your wife stays or goes, your daughter will keep hurting and keep internalizing what has happened to her parents. Please, get her help. For that matter, your son probably needs to go to therapy too.
As for asking your wife to move out... Before you do, decide if this is what you really want. I would suggest talking to a lawyer and an IC before you do anything rash. No, scratch that. I IMPLORE you to do that. You need to be sure that asking her to move out is right for you (legally speaking) and right for your children (in terms of their mental and emotional health).
Good luck.
Me: 28 H: 30 T: 9 M: 7
WAH: First half of 2017. Round 2 started in Spring 2018.