is there anything quite like this? quite a strange premise but it does seem to fill a niche of "suddenly child" where: A) the child(ren) is a newborn baby rather than a 5 year old or something B) the child is the MC's child rather than someone else's C) the other parent is actually part of the story, and D) it's an SoL rather than an isekai or something.
if anyone has anything else in this same niche, do share it - reading this again has given me a craving for more.