@Missdotty123,
Ah, Buyer's Remorse.
You're not the first person who ever had it, where you've got the trappings of a happy life but your eyes are wandering and you're wondering if that's all there is.
You won't be the last-ever person to feel this way, either.
Consider the consequences if you follow through with anything other than coffee with a friend. Even unmarried people can have nasty custody battles.
You might not give a damn about your partner (aside from a throwaway lines about loving this person dearly, the rest of your post is all about this other guy), but at least I would hope that you care about the future of your child.
You need not stay with your partner forever, but you might want to evaluate what it mean to cheat, and what that teaches your child about love and relationships (and yes, your child and your partner will figure out there's something going on).
Really love your partner, like you claim to? Then there's no reason not to go to coffee. Take your child, or your partner, or at least talk about them. You know, like people who aren't looking to cheat will do.