Lot of us have bin down that same road you have taken and the journey is full of bumps and surprises most painful... svolt has raised some very good points already for you to consider...
It will take a lot of work with good counselling and therapy to get to the bottom of whats going on within you...people dont usually stray from someone they love unless they are feeling afraid of closeness/intimacy born of fear...something bought into the marriage from childhhood that usually has nothing to do with the marriage at all...and when they feel afraid will run to another woman or man....
You will only run from someone you really love as they are the ones you will feel the fear of hurt from, (old memories of pain and hurt) and will run to someone (OW) you dont love because it feels safer, and yet believe that what you feel with this OW is true love... Its a kind of infatuation that is difficult to shake and one can beleive its the real thing... it feels so real with the OW OM when theres no responsibilities of socks an jocks to wash,...theres a freedom to say anything without fear of criticism as there is no investment/committment here yet so one thinks that they have so much in common...freedom to have great sex without feelings of having to perform...no kids and house payments to worry about...no garbage and house chores to do...no lawns to mow etc...and no same ole routine and boring mundane familiarity in contrast to the exciting exploration and discovery of someone new....so it makes the OW OM look so much more desirable to be with than ones own spouse....but its fairyland stuff....!!!
The reality of the fantasy only hits when the big D has been decided (and done with in some cases)..and the new couple commit to each other then the responsibilities of their marriages that they felt so keenly before now transfer to their new relationship..and quickly become even more frightening and burdensome to them as time together wears the crackle and crinkle of great sex and sparkling exploration down to mundane familiarity and the old fears return to plague them ....so if these fears are not dealt with at the level at which they were created they will continue to cause havoc until they are addressed...
Many choices are available to you...here are just a few I have come across from what others have done in similar situations..
1. Shut the OW out completely while you tend to your inner turmoil by filling your mind with other thoughts and work and other distracting things...
2. You can be open about it and deal with the hurt and pain and possible revenge and rejection...this takes courage and honesty..
3 You, your W and your friends could get together and talk it out so that its out in the open...from a situation like this some have formed a group sex thing or agreed exchange of partners between them...some have worked some not...
4 Seek counselling and therapy..not for or on your marriage..but on you ..on your deep negative motivations of hurt fear and pain...these are the driving forces behind your behaviour and feelings...find these and release them and you will find peace and inner calm compasion and love of self and others...
You have a lot going for you at this stage and it will depend on your decisions now as to whether your marriage stays together or folds up... however 1. you must love your W for you to be reacting as you have even if you may not understand it yet and she must love you to be reacting as she is...
2. She hasnt left you...although her comment about finding men is motivated by anger...
3. You both at this stage want to do something about your marriage...