SUBREDDIT: r/relationships
TITLE: Me [22 M] with my SO [23 M] of 18 months, found out he's cheating. Want to break up today. Please, how do I handle this?
POST: I just found evidence my SO is cheating on me. I'm the only one awake at this moment but his mom is the first one to get up and get to work. I see her as my own mother. Do I tell her her son has been cheating on me and say goodbye? Do I just thank her for everything? Do I act as if nothing happened, talk to her son when he's up and just dissapear out of her life before she's back from work? 

I don't know if I should have a conversation with him about the cheating and ask about his feelings or details and go through the tears and apologies or just simply say I know and leave his life like that just after he wakes up. I'm so worried he'll do something stupid after the breakup, he's all alone at home when I leave during the day. I'm so devastated.
TL;DR: 
SO is cheating, want to break up the moment he wakes up. Conversation or just coldly leave, say bye to his mom or just dissappear out of her life?