I understand why you want to fight for your marriage - but it may be that now, the best way to fight FOR it is to open the windows and let the truth in. What you've been doing is just keeping you stuck. And you are losing respect for him every day that this goes on this way.
Don't be afraid - if your marriage does collapse, there is a whole world out there of adventures to be had. But I think it is equally likely that your H will be somewhat relieved when things are out in the open, and that he'll choose you. After all, as I said before - he hasn't exactly been in a rush to go off and be with her, now, has he? She's probably getting kinda mad at him by now.
