I've been following this thread since the beginning, and I've been in your shoes up to a point. Once my wife started going black she let one of the guys get into her head, he got attached, seeing her behind my back, and looking back on it it is something we survived.
I only tell you this to encourage you that anything is survivable if you both want a marriage to survive.
From your posts I'd say you're hurting--bad. You've been betrayed on several levels, the woman you put your trust into is going off the deep end, and a guy who you gave the gift of allowing him to fuck your wife has betrayed you as well.
Before you can decide on anything you have to know where you are and what you want yourself. This is such an emotional issue I'm not sure most people can think this through on their own. I can tell you in general this forum is not the place to get the advice you need to handle this. Find a good marriage counselor or clinical psychologist for yourself to help you deal with this.
Once you know what you want--then go after it, or walk away from it.
Your wife is not showing you any respect by spending days with this other man, telling the family, and going through the preliminary motions of breaking them into the fact that she may not be with you much longer. Her actions speak loudly.
The questions you have to deal with is if you want some low life who would make a run at your wife after you were kind enough to share her with him raising your child. In GA you're going to have a hell of a time getting custody. However, if you are going to raise HIS child, you need to get some guarantee of him paying some of the expense (unless you can adopt the child and shut the father out). Bear in mind that if he choses, even if you and your wife stay together, he could insist on visitation and continue contact with your wife over the child. In all this it is time to find you a very good lawyer before that kid gets here, just so you know where you stand.
And finally, if you can forgive the transgressions, and want her back, it it time you demand the respect you deserve, grow a pair and take control of the situation. Fight for her if you really want her. Romance her, take her to places in your past with her that provokes fond memories--you do have a history and a child together. Make her fall in love with you again. You've been straight up here--she needs to understand that her black lover is the intruder into the relationship, and his actions are just wrong.
Of course there is the other side of this too. If the pain is too much, if she is too far into him emotionally to think straight herself (keep in mind that she is pregnant and thus "hormotional"), if you're too tired to fight for her, or you don't think she's worth the effort--and you are the only one who can answer that--if all those are "I'm done," then the next word may be in order. "NEXT!"
You have some big psychological, legal, marital, emotional problems here bro. Fix what you can. Doing nothing is only going to drag it out and make things worse.
It is survivable if you want it to be. Good luck and hang in there. Regardless it is better later on.