Wow, increasingly intriguing where the child comes from, but I already have a hunch that it may be Inoue's son or, why not, another adventure of this.
To be honest, I empathize with the MC's past, but that doesn't mean being a home breaker, I like weird manga, with NTR touches if they are yuri, of a girlfriend cheating on her boyfriend with another girl, and I tolerate it in an anime or doujinshi H, but not here, the MC's attitude of justifying her affair with a married person seems shameless to me.
The plot and the mystery boy is the only thing that keeps me here, I hope that in the end it is known who that boy is, and we can see an emotional and moral growth of the MC, regretting how he got to that point, and letting go of that person, the only thing he does is a whim.