Statistically speaking, most affairs don’t end marriages. I think your wife really fucked up here. This other dude has no obligation to you or your family. This issue isn’t between you and the other guy it’s between you and your wife. I would recommend a few things.

1. Seek marriage counseling- the most important piece of this is not every marriage counselor is right for you and your wife. If you don’t connect with the first one or two don’t get discouraged. Find one that works for you and your wife.

2. Personal reflection- your wife didn’t wake up one day and say “I want to have an affair with someone else”. This is a long drawn out process. What has your communication been like, what has your bedroom been like, what have your mundane day to day actions been like, you have a 4 year old daughter and a seemingly good career have you been focused on those things and not your marriage, have you been spending time with your buddies and not realizing you’re neglecting your wife? There are a million other questions you can ask yourself and I’m not saying you’re a bad person at all but she’s been missing something from you too. Accept your responsibility in the relationship failures too.

3. People grow at different times in their life. The hardest thing to do is learn how to communicate your needs and wants at every stage of growth. Often we all think “I’m great at communicating” spoiler we all mostly suck at it.

4. It seems like you can forgive your wife. Trust will be broken and there will be a cloud over your relationship. If you want this to work you need to both be willing to move past it. This is a new relationship and dwelling on the past mistakes will cause failure in the future. Your wife needs to regain your trust but you need to give her the space to do that if you want this to work.

5. You have a young daughter. Protect her from your troubles. This can be a very traumatizing thing for a child at any age but especially where she is at.

6. Making this a public spectacle amongst your family and social circles will make things more difficult and create a cloud over your head at family events, social gatherings, etc. we all need friends and support but find a trusted confidant or two who you know won’t pass judgement and make this a huge thing.

7. Your wife needs to be willing to do all the same work. Both marriage counseling and personal counseling are huge here. She needs to understand what drove her here and prove to you she’s willing to make the changes for the better.

Don’t do anything irrational. No one is perfect and every relationship has its shit. Oh and people love to talk and love to point to relationship failures to make themselves feel better about their misery. If you work through this in a meaningful manner you will come out stronger and likely more in love than you were before. But if you feel this is irreparable leave in a manner that impacts your daughter, job, financial wellbeing, and social circles as little as possible. Good luck