You aren't alone....
Shena,
Given your situation, it would be to your and your wife's advantage for both of you to read:
Baker, Robin, Ph.D. 1996. Sperm Wars: The Science of Sex (BasicBooks, 319 pp. hardcover).
Good-used copies of this fascinating, easy-to-read "science for the layperson" book can be obtained from (e.g.) Amazon.com, or possibly from a nearby library.
A point Baker makes, somewhat incidentally, is that among married couples where the wife has one or more lovers, her first child will most likely be sired by a lover. Her second child will most likely be sired by her husband. Her children beyond two (if any) will, with increasing probability, tend to be sired by her lover(s). Baker assumes, in these cases, the wife keeps her infidelities secret from her husband. He seems not to consider the apparently-increasing numbers of couples in which the wife openly takes a lover (/lovers) and the husband accepts his cuckold status, as in your case, and/or even encourages his wife to take lovers.
To indicate you're not alone: Baker states, "On average, about 10% of children are not sired by their supposed fathers." He goes on to say: "Actual figures range from about 1% in high-status areas of the U.S. and Switzerland, to 5 to 6% for moderate status males in the U.S. and Great Britian, to 10 to 30% for lower-status males in the U.S., Great Britian, and France." He continues: "Moreover, the men most likely to hoodwink the lower-status males are men of higher status." (Page 124.) Again, the author assumes the women impregnated by men other than their husbands or long-term partners keep their infidelities secret.
shena said:
.... He [my wife's lover] then said to her maybe you'll have a baby for your hubby and she laughed and said yes, and the wimp wont even know. ....
If the baby is black, as you said will be the case in your subsequent post, then obviously you would know — even if you didn't know already (assuming you and your wife are both white).
shena said:
So, what must I do now, I'm a bit sad as i know I'm poor at satisfying [my wife] and the baby is obviously not mine. But, as I'm a fem type of guy, I guess I just have to accept this. I want to ask my wife at some point about the baby. I'm just not sure about all this.
If you want to remain married to your wife, as I gather you do, and given that when her black baby is born there won't be any doubt the father is not you, you need to have a long talk with your wife. I suggest starting at (what for you was) the beginning, and tell her you discovered her fucking her lover when you came home early from work that day. Also point out that since you and she did not fuck (or fucked very little) during the time period when her baby was conceived, you consider it unlikely you are the father. Tell her that since it will be obvious to all her lover, not you, is the father if her baby turns out to be black, the two of you need to come to an understanding about the future of your marriage.
Given the comments in your second post:
shena said:
Every month now I watch my wife's belly grow with another man's embryo, and my wife is happy and making love to him lots as she says I'm a sissy and I'm too small to satisfy her, and we don't have sex any more. .... But as I love her I have no option but to accept this, as I realize he has cuckolded me .... I was too ashamed to admit he is a big black man, and the baby will be dark.
indicating you are willing to openly be your wife's cuckold in order to maintain your marriage, you will need to be prepared to lay your cards on the table and tell her you are willing to help her love, care for and raise her baby, regardless of paternity, including babysitting when she is out with her lover(s), and that you are also willing to do a substantial amount of the housework in support of her extra-marital sex.
It will be best if you sort these things out and come to terms with all this in your own mind before initiating the necessary discussions with your wife, so you don't appear to be indecisive and unsure of yourself. That is, it will be best if you can talk with your wife as a man who "knows the score" and understands the implications for yourself and for her. I suggest trying to avoid appearing unsure and seemingly not knowing what to do.
Good luck, and best regards—
Custer