Losing my fiance, feel like I'm losing my life. I'm really not sure what my actions should be?

My fiance and me have been together for almost 10 years. We also have a 5 year old together. Our relationship although long has not been perfect. I left someone to be with my current, and thoughout the years we have both cheated on each other, although we have managed to forgive each other and we end up back together. Recently I found out she was having relations with someone she works with, and this has completely ripped my guts out. Although she has done this to me, I still wish to be with her and work things out. I realize most people in my situation would head for the door immediately, but I still can't shake this love I have for her. She has told me she doesn't want to walk away from us either without trying, but at the same time she has been extremely distant from me when we are around each other. She doesn't like to kiss anymore, she doesn't like to be close, we have made love a few times, but that confuses me even more. She has said that in order for us to get better, I shouldn't be nice to her, because that makes her feel sick. I have asked for her to be affectionate to me, because that will help heal me, but she has also said she can't do that either. All I have asked for from her is that she needs to make me feel wanted, and that I want affection, even just a little. She claims to feel like she is floating around in a fog, and can't make clear decisions right now. I really don't get that at all. Well, last night we got alot out on the table, and it basically came down to her telling me I should move out. I have been contemplating selling the engagement ring which should at least fund a new place for myself. She wants the ring, but only because it is pretty to her. Can't even describe how much that hurts. Anyways, within this conversation, she almost started getting excited when we were discussing what she would keep, and she basically wants everything. It appears to me that I mean nothing to her anymore. She has been still talking to the guy she was messing around with, but she told me last night she told him through email to leave her alone so she can focus on her family. Here comes my main question: am I fooling myself into believing her that she does care about our family, but that I need to leave her alone will she gets her thoughts sorted out (fog), or does it sound like she is only wanting me to stay so she will have the money to keep doing whatever she wants? Understand, although she works, she would not have alot of extra money to pay for rent, our daughter, etc. I have already told her I would file myself for child support so she has gaureenteed money coming to her. Anyways, this whole thing is completely destroying me, and although I'm fighting so hard to keep her, I'm not getting the same feeling back from her. I'm completely lost.