@Groove328,
Sounds like both you and your wife kind of checked out of the marriage and the family. Problem is, your child needs you. You can't **** around with that.
So choices have to be made - by both you and your wife. If you're going to work on your marriage, then go all in. Block this other woman, chalk it up to curiosity and let it go. Go to counseling and sort out what goes on in marriages, particularly how the dynamics change when kids are involved. And seriously consider taking a parenting class - BOTH of you - because an authority saying your child needs to know the ABCs etc before school might go over better than you saying it. And you need to commit yourself into your child and his/her care as well. If your wife won't teach the ABCs, then it's all on you.
If you are not going to work on your marriage, then be honest with your wife and tell her now, before she maybe gets pregnant again. Do this independent of whatever is happening with the side chick.
Be prepared to take a financial bath. Divorce ain't cheap, particularly when there are kids involved. Even perfect no-fault divorces handled with no lawyers and via mediation have other costs. Your child will have to shuttle between your place and your wife's. You will both be hampered when it comes to employment opportunities, unless you want to put your kid on a plane and shift custody to school year/summer rather than (perhaps) every other weekend or whatever.
Get counseling if you end your marriage, too. Get some tools to handle the disagreements that will accompany the dissolution of a marriage and learn how to effectively co-parent. Parents who divorce amicably are doing their children a great service. Those who get into screaming fights at the drop of a hat are damaging their children. Decide which way you want to be.
But if you are unhappy in your marriage, end it. Don't stay together because of your kid. That's a horrible reason to remain in a marriage. All it does it teach your child that love is meaningless and marriage vows are ****, and that all that matters is the almighty alimony/child support dollar and the equally almighty family disapproval.
So forget about the side chick and think about what you want to do. How do you want next year to look, next five years, next decade, next thirty? And how does your wife want those years to look? Figure out if you're on the same page, or if you can get there any time soon.
And for God's sake don't have another kid until this is sorted out.