If she wanted to see what else was out there, she should've thought about that before the wedding.
I'm sorry, but I'm going to be blunt.
You are NOT her best friend anymore. If you were she would not hurt you the way she is.
She does not want to be your wife anymore. She wants the benefits, the security, of sticking with someone she knows while she gets to go play the field. You have become her fallback guy. HUSBANDS are not supposed to be the fallback guy.
She has given you a wake up call. She has told you point blank she wants to screw around. Yes - SCREW AROUND. "See other people" and "See whats out there" means the same thing in Chick-speak as it does in Guy-speak. She's not going to go out looking for someone else just to be friends, she's out there looking to see if she can do better than you.
Now is the time to take stock of what YOU want. You say you want her, but do you want her when she treats you like this? I would hope you would want a woman who treats you like a wife should treat a husband - with respect for him as a person and with the loyalty those vows described. I would hope you realize that you are WORTHY of having a wife who doesn't feel like she's missed out on life, but who feels that you make her life complete.
You deserve so much better than how she is treating you. My instinct would be to say cut her loose and let her find out how the Real World is, but I understand that you don't want to let go. I can empathize with that, so the only viable option is to try counseling. You and her, or just you alone.
I can tell you from personal experience that what feels like the end of the world is really not. As much as I loved my Husband, I couldn't accept how he treated me. If we could've worked it out I would've been happy, but even though we didn't, I don't regret my divorce.
The more time you spend trying to save your marriage single-handedly, the less time you will have to find happiness and a stable marriage to a woman who deserves you.