Editing advice: your text is often too big (even considering how shitty the bubbles are here) and you're missing a lot of punctuation, especially periods. Don't use Japanese punctuation (vertical em dashes, vertical ellipses, etc.)
TL advice: don't try to stick to JP structures and phrasing that much. It can make things really awkward to read. Your goal should be to not only have an accurate TL, but also something that sounds natural in the target language.
@Emarmei Inseki Description: Sex involving in-law, step, or adopted family relatives. Notes: Requires the incest tag.
I'd make the case that the brother didn't deserve her. Tell her the best way to get revenge is to get pregnant with my kids instead, while the brother kicks himself knowing he was wrong about her being barren.