I know how she feels with this guy online. In my marriage, the things I needed were so lacking that when a guy came along that said those things I needed so badly to hear, I was hooked. It feels like a soulmate. She's probably thinking this.
Ok, who does she respect at this point? Who might snap her into the reality of the situation? I remember being so "out of it", so out of reality. I was sucked into this fantasy world that was so addictive. Telling her parents could do it. But, be prepared with proof because she will twist you into something that you are not. She will rewrite history and make everything bad in your marriage into something even worse. She WILL be angry. But, if you talk to her, and she won't stop....if you want to fight for your marriage, you will have to do this to try to save it.
This six month period she is giving is meaningless if she is still in contact with the affair partner. Just like if you went to counseling while she is still in contact...it wouldn't do anything. SO, once you get proof, you give her a choice. You can't make her stay, but you say that you can't live in a marriage like this, that you believe your marriage is worth fighting for, and that you will need to cut off the internet to feel safe in your own home, etc. You get the idea.
Letting her friends go....I did that as well....nothing matters anymore except the words that this man says to her. It's like a drug, it really is.
I didn't consider myself married either so that it would give me the "ok" to do what I was doing. When we physically separated it only became worse. Try to save your marriage with her in the home with you.
Gather enough intel that you can prove that the affair is emotional, sexual, and predatorlike in nature if possible. The quicker the better since you said you only have 2 weeks.
Yes, it is possible to create an atmosphere of love/forgiveness/dedication/effort to change in two weeks. Just love her. She will look for every reason to hate you....one thing I remember that would really "get me" was the victim/puppy dog look....don't do that. Be confident, kind, loving, and committed, but not a push over. When you have that conversation about limits she will know you are not a pushover, she will also know you love her if you do it right.