So just write mom then? This isn't one of those words that can't be translated. There are no hidden nuances that will only come through by keeping the original japanese. Mom or mommy are perfectly fine translations.
I don't know who wrote the description, but you don't "cheat on another woman" you cheat on your wife. The other woman is with whom you cheat, no the one being cheated on.
Makes sense to add TL notes about certain details of korean culture, but don't add explanations as to what is going on. The dialogue is supposed to convey that.
@PankoPanko
Agreed. Though I must say the author can write some good combat scenarios, it's taking too long and there's been far too many interruptions. Hope everything settles down next chapter.