Continue to concentrate on you and your son.
"If something cannot go on forever, it will stop." Herb Stein
Listen carefully. She is being very honest with you about her feelings. It is hard to accept. Please do see her as finally being honest. Go to the boards on Mismatched Libidos and the one Married withoutRomance. You will find much knowledge there.
Now for the no so good: A regular counselor is not trained for these things which call for one who is also an MD and a sex therapist. When you say she has "met" this guy did that mean "in the flesh" or on the internet?
If she has not met in the flesh then I have a BIG WARNING:
These people search for their prey and are very good at what they do. http://www.ic3.gov/complaint/default.aspx
Now you have some information. I suggest copying everything that you legally can esp the "headers" of email. use Yahoo e mail which keeps transmissions.
There will be floods of cheerleading and advice that will come to you from this site.
dav,your post sounds strong and confident. you are moving forward, being realistic and taking of yourself and your son. you have a good head on your shoulders and will come through this scarred but not broken. yes, both you and your wife will live with the consequences of her decision, but i hope that as you heal and come to terms with the upheaval in your life at present, at some point you will see the power that you have to make your own decisions and guide your own life---regardless of what she does or doesn't do. i can assure you that eventually she will realize what she has given up--though it may not be in the timeframe you would wish. she's headed for brick wall--the question being "when", not "if". hold your head high. we're in your corner.
I'm sorry to hear what you're going through.
dav, your wife wanting her cake and eating it too does strike a familiar chord, and from that view i do agree with freelance. how you should approach her behavior will likely be addressed by other experienced folks who have been in your situation and have either rebuilt their marriages or moved on with their own lives. again, i write to give you some perspective on what your wife could be thinking or feeling based on my own experiences.
having talked with and read the stories of many women who chose affairs, i can say that it seems there is something peculiarly similar about us. insecure women with a poor sense of self who are looking--desperately sometimes-- for validation outside of ourselves. the small romantic gestures your wife makes---though cruel and thoughtless of your feelings, i agree---i think are an ultimately good sign. to me, it is an indication that you have something that she needs and does not want to give up. she probably is also feeling some guilt for the suffering she is causing you, too---another good thing as far as i am concerned.
when i was in the thick of my affair "fog" i had withdrawn severely from my husband. about a year into it, i went to him and told him i was unhappy and considering a separation. i did not confess my affair to him, and i will never know whether he suspected, but he is no fool. we had several intense and excruciatingly painful conversations about where our lives were going. he was staunchly in the camp of reconciliation and saving our marriage. i was luke-warm and not-even-half-hearted in my ability to invest in and "be there" during that dark part of my life. i know i hurt my husband deeply--even without knowledge of my behavior--and it has taken some time for me to own my actions and feel the weight of the responsibility and guilt.
my husband is a very self-less guy. he made it clear that he was going to give our marriage his best shot and that if it failed, it wasn't going to be because he didn't give it his all. he stepped up his game, he gave me his attention, his time. he backed off when i told him i needed space. he was very consistent. i was all over the place. i did not deserve his love and compassion, but it was consistently there. maybe if he had been unkind, it would have snapped me out of my fantasy more quickly, i don't know. it may have backfired and i would have self-destructed and thrown everything i had away. what i do know is that in spite of my behavior, my husband's support and opinions have always been important to me. your wife, on some level, knows that you are important to her. important enough to share ten years of her life, important enough to give you a child. that she still makes small gestures towards you tells me that you are still important to her. that is where your power will lie as you make this journey.