No woman, job or significant other is worth more than being unhappy. Yes it feels like a difficult choice to have a broken family but there is always options. There will be a reason why she cheated. She may of got bored of your marriage, she may not love you anymore or you may of pushed her out. If you stay together, get help. Try couples counseling and having open honest conversations. If she truly isn’t happy with you and you are not happy then go your seperate ways. Two single happy parents is a damn sight better than one unhapoy couple parenting. With that aside, the hard part is she cheated and she needs to be the one to leave. Pay for the consequences of her actions. Get legal advice and do what you can for your kid.
I hope this helps. Everyone deserves happiness. ?