Trinity is right.
Karen, you said, "So we will get an attorney " - sorry, YOU need to get YOUR OWN attorney. Don't share his - it will be a clear conflict of interest. He has hired an attorney to mediate, which is his way of saying to his attorney, "Do whatever it takes, but don't let my wife end this marriage and throw me out of my house!"
You need an attorney who will listen to what YOU need, which MAY include reconciliation, or may involve a peaceful dissolution - your choice.
As for sharing the same house during the separation - that is entirely up to you. Again, get your own independent legal advice on it (in terms of the fine detail, what you may do for him and what you should not) and then make your decision.
If at the end of all this, miracles happen and you decide to keep him, at least you will be making the decision with your eyes wide open and the benefit of sound, independent legal advice.
Getting your own attorney should not indicate that permanent parting of the ways is inevitable. But if at a later stage you choose that, then the groundwork is already done. If you choose to reconcile, there still should be no problem.
But you DO need to separate off legally for a while, to get a truly impartial opinion on what your options truly are.
Marg