Some people say that NRE lasts about 1000 hours, which just counts time actually spent together or in direct communication. So, she's still way in NRE- which does not excuse cheating, it's just something you should keep in mind if you want to understand her side of things.
People who are forcibly separated during NRE historically have done some pretty crazy things- my grandpa forbid my mom to date my dad, so they drove to Iowa, lied about their ages and got married. This is why people shouldn't make any major decisions while in NRE.
So, you've got a choice. You can hurt her, make her chose between her children and her lover (which being forced to make that painful choice would make many people consider the option between hurting and lying). You could do as much as possible to make her life really suck, to get back at her for cheating on you....
Or, if you still love her, you could try to understand how she feels, and try to work with her to figure out a compromise that will work okay for everyone.
Myself, I've found it much easier to stick with boundaries that seem to show some consideration for what the other people involved want- like when I was first dating a new guy, his wife wasn't comfortable with us having PIV, but she was okay with safer activities, so we did a lot of making out and cuddling and various other things, it was nice taking it slow and it meant more when she did relax the boundaries.
In another situation with another couple, the wife decided she wasn't comfortable with me doing ANYTHING sexual with her husband, she knew I still wanted to, she knew he wanted to, but she wasn't willing to even discuss it or say WHY it was such a problem, and she's frequently left us in situations where we'd have opportunity to ignore her boundaries, if we had less ethics or didn't care so much about her feelings- but sometimes it makes me wonder if she doesn't care, or she doesn't understand, or if she's testing us or what. It's hard doing the right thing to make someone else happy when it seems like they don't care if you're happy.