Paternity determined

SO one question has been answered .. A is the father of baby girl. Not P. One sigh of relief but yet P is the father of Baby Boy. :( and i found out that A has another son .. only 9 months younger than my daughter. I cant consider it cheating since we were never together but where did he have the time? He was with me 4 or 5 days a week during my entire pregnancy ..
Took him to take the paternity test ... havent heard from him since .. not once has he tried to contact me or even seem to want to meet his daughter. He was part of her life for 5 months but denied the whole thing in front of the court. uggggh! Is it for the better? How will I ever explain it when my daughter grows up? What kind of pain will she go through because of my actions? And now P is being a jerk too. He has been part of her life since she was 7 months and now doesnt even ask about her. She calls him daddy and I guess just like most fathers do will break her heart like mine broke my heart when i was just a child. Again .. how did i get here .. ? How did i ever think I was better than ghetto? 2 children 2 fathers .. and not one around to help out.