From my perspective: I would break up with you for having a child with a woman that you once were married to and obviously are still very much emotionally attached to. I would let you have one another and raise your child as a family unit.
As for the part where I would donate my egg. That would be a total double standard and I'd not do that either simply because it would be a slap in the face to my new partner just as your donation is a slap in your current girlfriends face. I have no idea why you would think that what you have done would be acceptable. Particularly since you didn't even discuss the situation with your current partner. You have no respect for her in that regard and why I think you should just remarry the mother of your future child.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion