That is an unhealthy way to think about family. Once you make that commitment, you shouldn’t leave him behind. I’d recommend attempting to gain custody of the child.
Imagine being so dissatisfied with having a son that you proceed to have 14 more and then finally get a daughter. These kids will not be able to go to college. These kids won’t get the individual attention kids need. These kids will suffer in life due to this moms greed.