1. So, they were all received? She didn't send any?
Ya know, even if she's keeping to her comitment, she can't stop the guy from talking to her. She did have an affair with him, so she can't pretend he suddenly doesn't exist. You can just be honest, say, hey, i noticed this. I didn't spy or anything. I just noticed. Now, given the situation at hand, i find it rather odd. I don't demand that you explain, but it would be nice if you would.
2. Tell her you really want to work things out, then ask her how hard or inconvenient she would find it to switch shifts. Mention how helpful that would be to your marriage. Again, this is just my opinion, but put it out there as an idea to fix things, never demand anything, never put on the 'but i'm doing/giving...and you aren't' face. That always, but always, annoys people and makes them detach. If you think it's fair, even a bit of 'manipulation' works, along the lines of 'remember when we started out, we got along so well...we can do that again, if only we had the time and open mind to do it'
In the end, you know her better. Plus, my thought on this is, when your mate isn't giving 100%, you are inclined to give less, for it to be fair. But, when you give even more, they tend to follow your lead.