Has your H ever indicated the reasons for the OW. What need is he satisfying? It is natural to feel like you do. I have many of the same emotions and you just want to reach out to your spouse and make them all go away. It doesn't work that way. I did set boundaries early on like NY Survivor suggest. Can't say for certain that everything is over cause she works with OM but I wan't to beleive it is. Basically said to W that she must end it if she wants to stay together. This is something that you will have to figure and if you do decide if and what boundaries to set, remember timing is everthing. I would be careful of pushing him away but "tough love" can work.
Update to my sitch. I saw counselor yesterday. Wife and I go to C separately. Not much encouraging from the counselor. She indicates that W just doesn't know what to do (stay or go). C said that she is going to try and bring W and I in together to try and start solving issues and to try and determine if W is still interested in saving M. C knows we are not progressing and I am afraid to push much because it goes against DB. Anyway, the C's office might provide a safer environment for W. I know my situation is not as extreme as many of the others on this board but I am scared. C says that at least she is still living at home and that there is always hope. All true but still not much to hold onto. Looks like it is time for a miracle.