Thanks for the translation!
The only blameless one is Fuyuki IMO (though she's in a fake relationship with someone who may or may not "like" like her). She's done nothing wrong. Eri used Kyou. She seemed to be running from her feelings for Fuyuki which started this whole mess. Kyou vented his frustration on the other girl. Loneliness and feeling undervalued are not justifiable reasons to cheat on someone, so I feel Kyou's sins are heavier. The other girl was being a homewrecker. She knew Kyou was dating someone. She has some fault in the situation as well.
The next chapter should be interesting. As much as I want Fuyuki to be happy and be with Eri, I want her to value herself more. Eri is emotional and isn't going to make good choices right now.