If an A exists you are right, it IS a complete disrespect to you and your marriage, it's the worst kind. That said, remember it's not about you. Your W did not set out to disrespect you and the marriage. Generally our spouses "slide" into an affair gradually. Once they're in it, it's too late. That's different than deliberately setting out to hurt you. My DB coach was very helpful in allowing me to get perspective on this and move forward, may be worth talking to one if you haven't already. The first call I had after discovering the affair(s) was the most valuable conversation of my life.
Here's what I went through if it helps: I was married for 15 years, over the course of the marriage, I think we had a "shouting argument" maybe 3 times, and my W was reduced to tears over something having to do with the marriage twice. We parented together well, didn't fight about money, were respectful of each other etc. Overall, I thought everything was good. We weren't very connected, but I'd gotten used to that.
My W is an intelligent, independent woman. I never thought in a million years she would be capable of having an affair. I honestly would have bet everything I own against it. After my W dropped the bomb, I tried to DB but was getting no results. The W I knew just wasn't "there", I was suddenly living with an emotionless being who treated me like a business associate. Polite, but cold.
Over time, I got suspicious and started asking leading questions. I was trying to open the door for a confession, or at least a discussion, but I got nothing. If anything, it made me doubt my suspicions. Like you, I finally "snooped", and discovered a 6 month EA, preceded by an 8 month attempted EA (infatuation), preceded by 2 incidents of "one-nighters" that did not go all the way. This was over the course of a few years!
Throughout my marriage, I had assumed that if my W cheated on me, I would walk, without looking back, and try to get custody of the kids. I spent no time thinking about it though, really, because it wasn't even a possibility.
When it actually happened, I had to gut-check and dig very deep about what I really wanted. I was somewhat surprised to learn that despite the deep disrespect, what I really wanted was my W back and an intact family for my kids. I caught a lucky break because the last EA had ended literally 7 days prior to my discovery, cut off by OM, in response to my W's escalating for more physical connection.
I know many on the forum feel differently, and they are probably right, so these are just MY feelings, and not advice. For me, I confronted OM right away and made it clear he was not to contact my W, and probed for facts. I also got my W to tell me everything, and tried to discover as much as I could through investigation / snooping. Here's why -- I wanted to know it all so I could process it all, forgive it, and move on. I didn't want to make serial discoveries and get thrown back to square one of shock and grief, and I didn't want to spend my life wondering about what I didn't know. For me, it was necessary to have it all on the table, paw through it to my satisfaction, and then forgive everything and move on.
Through this process, I discovered that my imagination will fill in details that are often far worse than the facts. I think that's why people advise against snooping. If you know a little, that's the worst because you will assume a lot, and assume the worst. Better to know nothing or everything in my book, and often you cannot and will not ever know everything. Also, your W may be very angry about the snooping and that can do a lot of harm. For me, my W was not mad, she viewed it that she had already violated the trust in the M, so my snooping didn't really matter.
As others have pointed out, you will go through the stages of grief and it will be hard. Find a support structure. Find people to talk to and vent. You will be tempted to try to work through your feelings and hurts with your wife, but you can't, you need to take it somewhere else.
Just know that it will get better, and you will get through this. Please do spend some time gut checking and figuring out what you really want.
--Accuray
Married 18, Together 20, Now Divorced M: 48, W: 50, D: 18, S: 16, D: 12 Bomb Dropped (EA, D): 7/13/11 Start Reconcile: 8/15/11 Bomb Dropped (EA, D): 5/1/2014 (Divorced) In a New Relationship: 3/2015