If it helps you any, I am in the same boat. I have 2 small children, we've been together for 16 years--married 10 of them. I found out back in April that he was having a too-close for comfort friendship with a woman in his office that was going through a divorce. I knew it was more than what he was telling me... which gave us quite a rollercoaster ride these past months. He also said he wanted to leave for a while and think things through because he was depressed... this was after I found-out more about his relationship and realized it was a very emotional affair with kissing (at least) involved.
My thought is this--you don't take time-off from a marriage, if anything, you did that already and that's why you ended up where you are now. If he wants to take time to himself, he should go to a counselor and figure things out. I have put my mind to it that I deserve better than being second best... which is what I would be if he left because you know they want to experiment how life would be with the other person. However, it's all a fantasy until they start raising children together and managing the household. Reality is that you need to be strong for your children and yourself... maybe even for him. I have told my husband that if he chooses to leave, he will have to tell his family and that the next step will most likely be a divorce-- which we've both decided at this point we don't want. It has been the most stressful and exhausting months of my life... I never thought this would happen to us, but such is life and God gives you what you can handle. Stay strong, read and get as much positive support as you can. Trust your instincts and have faith that God is going to help you no matter what happens with the relationship.