I would say, an initial response depends largely on who you and your friend "like" amongst the cast of characters. The Epilogues by no means let anybody off "easy", but there's definitely characters who get away from the narrative relatively unscathed and untarnished by their depiction at the end of Homestuck.

I assume you've already consumed all the content there is WRT to the Snapchat ending; the content presented there does not line up with the tone of the Epilogues largely.

Be prepared for a shift to a lot more adult themes.

At the end of the day, do not feel pressured to consume it if you worry about it altering your perception of something you previously enjoyed. If your friend is already feeling down about the conclusion of the comic, perhaps give it some time before you guys tackle the content presented in the Epilogues; some space to breathe and extrapolate your own feelings first.