Don't beat yourself up. We have all made the same mistakes as you. But you have options. You start to do what works now. You also have information that you can arm yourself with.
You know your wife need you to survive. She couldn't make it on her own. She has already proven that to you. Stop taking care of her. Do you cook? When you do cook enough for everyone, but don't make a plate for her. Do you buy her snacks when you go grocery shopping, don't do that no more. Do you buy her favorite soap, don't no more.
Let me say again, she has already proven, she can't take care of herself without you. Don't be punitive, but make reality come to light.
During her walks, take the kids out and go have fun with them. I'm glad you told her you don't agree with her affair. Good Job. Now it's time for some action!
M:37 W:37 T:11 M:10 S17, S13, S10, S4 BD:06/28/17 OM confirmed 07/20/17 Recon the M 10/29/17 Working hard:2gether
Onward and forward
This process is not a sprint it's a marathon! Patience, Patience, Patience.