[This message edited by PoLo89 at 2:34 PM, November 4th (Monday)]
Your H needs to be honest. He cannot continue to lie to you. It is disrespectful, and you deserve the truth in your marriage and life. If you are going to forgive him, you need to know what you're forgiving.
I would start the 180 (healing library, BS Faqs, question 11), insist he go to IC, and find an IC for myself.
Being betrayed is very hard, and takes a very long time to recover from. His lying is only going to make that worse.
You aren't alone. Too many of us have been blindsided by this kind of crap. You will find friends here.
There is a strong possibility that you still don't know all the ugly truth. I would insist on a polygraph to start. You cannot heal unless you know what you are healing from.
What you do next is dependent upon whether or not you want to work on your marriage or whether this infidelity is a deal-breaker. And make no mistake about it, even if his behavior WASN'T physical, it still was infidelity.
The Healing Library has so much useful information, and clear, purposeful actions for you to take. As do some of the posts in Just Found Out. Read and post here often. We'll help you through this no matter which path you take.
I think the first thing you should do is focus on YOU and what you want. These decisions do not have to be immediate, nor do you have to put a timeline on figuring out what you want. Do you want the WHOLE truth? If you do, make that a condition of R. Make sure that he KNOWS the lying and trickle truth has to stop, and if he can not do that, he needs to leave. I told my FWH that if I found one more lie, if he did not start telling the WHOLE truth, I was done. And, I meant it. Definitely follow through with whatever you decide.
Contact with her has to stop. Has he done that? He needs to cut ALL ties. Block her number, change his number if he has to, block her on facebook, and change his email address if he needs to. Whatever it takes to cut ties. I know he works with her, is that something that could change? Is that something that YOU need in order to consider R? The day I found out was the day he blocked her on FB, closed his email account, and we changed our numbers. He gave me every password/passcode he had, and I started monitoring the phone bill. That was the ONLY way I was going to stay, and he knew it.
There are a lot more things I could write, but honestly, I think your initial plan of action would be to figure out what you want/need at this point, and if you are willing to R. THEN, if you are, set clear cut conditions of R.
Hang in there, honey.
Me: fBH 46
Her: exWW 42
DDay: Nov 1, 2012
Divorced: September 17, 2013
He needs to stop the contact with her immediately. Not eventually. He needs to hand you his phone to prove there's no continuing contact, no deleting of anything allowed. If she is married, you need to contact her husband without warning him. Her husband deserves to know the truth, and it puts another set of eyes on the pair of them.
There are other steps to take if you are to gift him with the treasure of reconciliation.