I'm sorry, but "I need space," in my opinion, almost ALWAYS means "I need space in which to conduct my affair, unencumbered." That being said, you still have to give it to her -- but you DON'T have to pay for it, and shouldn't.
Stop pursuing her -- no begging, no pleading, no ILYs. See if you can get her to agree to 100% no-contact, and full transparency, during your time apart, and go to a good family therapist with you. If she won't agree to the transparency, and accuses you of being "controlling," then tell her you will proceed under the assumption that she is having an affair, and will make moves to protect yourself accordingly. No yelling, no ranting and raving -- just businesslike.
Puppy
Yup, exactly this, no chasing, no pursuing, you limit your contact now too, don't contact her until she contacts you.
You're expected to pursue her, to feed her ego because she knows you love her so much and she's the one who isn't sure.
Turn it around.
Agree with her, "I agree with you and how you're feeling because now I'm not too sure how I feel about you anymore either, after this happened I'm reconsidering everything, I'm young and I have a lot of options and I see that now. You should be with the OM, I've decided that I don't want to be with anyone who doesn't want to be with me, that would be settling and I deserve better, good luck with the OM, I hope it works out."
Don't be an a$$hole or a jerk about it, you need to realize pursuing her, being all sad, lonely, wussy like isn't going to win you any points, something killed the attraction between the two of you and this OM knew how to create attraction between her & him even if he isn't near her everyday.
Time for you to get out with friends and enjoy your single life. Let her go, I know it's hard to hear this but the sooner you let her go, the sooner she'll reconsider all of this and start considering that possibly she's made a big mistake when she see's that you've let go and moved on with your life.
