not sure whether this sentence is using "demo" or "de mo"

the sentence is:
X-san ga nakan demo, sumu you ni shitaru.
looking at the translation as well as my own, i come up with: i'll finish this so that you won't have to cry anymore.
I am trying to pin down which use of "demo" the sentence is using. I know demo can mean "even" but it wouldn't make sense to translate it as "even if you don't cry." The meaning "but" as well as the other meanings of demo also do not fit here.
so i started thinking maybe the sentence meant "de mo" instead, for i know that the particle "de" can be used to express the reason for something. but then it would be translated as "because you won't cry".
i'm still having trouble with particles when reading Japanese and I would greatly appreciate someone helping me understand this.

It's not nakan+demo but nakande+mo.
It's colloquial form of nakanakute+mo, verb + negation (nai) + te-form + mo (particle).

In addition to undrentide-san's explanation, probably as you already know, Gin uses Kansai dialect. This 泣かんでも is originated from Kansai dialect. (Or rather, ん, which is originated from Classical Japanese, still remains in Kansai dialect.)

泣かんでも済む means 泣かなくても済む/泣かなくてもいい "don't need to cry". 済む doesn't mean "to finish something" here.

i can mostly get the gist of what he's saying so far, but sometimes he throws in something like "nakandemosumu" which i would probably never have guessed meant "nakanakute mo ii" haha. on that note, is "sumu" something like the equivalent of "ii" in the kansai dialect?

The sumu bit is standard Japanese.

ええ is いい in Kansai.

oh i see. the phrase nakutemosumu was never mentioned in my textbooks so i kinda assumed that it was part of the kansai dialect as well. thanks for the clarification.