What business would anyone want with a cheater and a child that isn't their's? I would understand if you want to be a part of the child's life if it was biologically yours, but in this case it isn't. You would just be raising a child for a cheater and her side piece. Why bear such a responsibility when it does not involve you in any sort of way? There's no relationship to salvage at that point and it's the child's parent's responsibilty to take care of. If that's the case, you might as well take care of every pregnant girl's child, since it also has nothing to do with you directly. It's not "mature" to spend your time and money on a child of a cheating girlfriend, who clearly doesn't give a damn about you. Have some self respect, break ties, find someone new, and let the cheater enjoy her new life.