Well, I'm not sure is has ended. That is question number one to resolve if and when we decide to take a step toward each other. I know it is not anything like what it was, simply by how she's acting, but I doubt all contact has been severed. She has no reason to yet.
Yes, it most assuredly is a question that needs answering and your marriage doesn't stand a chance if she's still in contact with OM.
And, if you don't know that she isn't in contact then she probably is.
Hope4us is absolutely correct. Complete and total no contact is the very first requirement for recovering your marriage.
Don't let her back into your home until this has been dealt with. Other posters and bitter experience has taught me that it's a very, very bad idea. My W came back to live with me and stayed in touch with OM, even visiting him a few times. I am dirt ashamed of myself for this - I basically offered myself as a host that she could parasite off of. Don't do this my friend.
Me: 46 W: 46 T: 23 M: 20 DS12 DD11 DS5
W left: 01/28/08 Discovered OM: 02/26/08 W back for 9 days: 04/08 W returned 05/21/08 EA/PA - 01/08-07/09 W's MLC 2008-2014 (realised this much later)