First, this is ALL on her, you did NOTHING to cause this. She is broken. The only positive is that she confessed, you didn't find out. Seems like 99% of affairs are discovered by the BS's (betrayed spouse). Sounds like her guilt was too much for her to keep inside which is a good thing.
Now, you need to focus on your well being, first and foremost. I strongly recommend you get tested for STDs. Don't ask your wife if you need to, tell her you are doing it, and be honest with your doctor why.
Are you concerned the baby may not be yours? If there's even a remote chance do a DNA test. You do not want to raise another man's child.
Talking with an IC that is trained to help with trauma will help you greatly. Being able to speak openly and freely without fear of judgment is incredibly helpful.
Just an FYI, there seems to be a pattern wherein WS's only confess as much as they think they need to in order to placate the BS. It's possible there is more to the situation.
If this guy has a partner she needs to know what her man is doing. She has a right to know. I waited five months before reaching out to the wife of my wife's AP and I regret every day I waited.
We all understand how devastating this is. You have found a great place for advice and support.
ETA: Do not sweep this under the rug. Do not let her do so. Doing so may provide a temporary relief but when this resurfaces, and it will, the damage will be much worse
[This message edited by WB1340 at 4:27 PM, Saturday, July 11th]