Not really well said. I think your question was simply "Does an absolute universal evil exist?" or "Does evil exist outside of our thoughts and feelings?" (not just how your personal tummy feels about something). Your feelings should have nothing to do with it. Existence of something is completely independent of how you feel about that something. In fact, if you feel happy about some belief then you should question your belief much more because of our natural inclination to believe whatever makes us happiest and to deny things that make us unhappy. I think you probably already know this.
The societal/social side-effect of believing in something has absolutely nothing to do with whether something actually exists or not. Yes, believing or not believing may have beneficial effects on some or all people but that still has absolutely nothing to do with whether something exists or not. This is true unless you want to completely redefine the word "Evil" like Ayn Rand has done. Philosophers do that shit constantly. Rand would probably tell you that something that impacts most humans negatively is "Absolute Evil" and "Universally Wrong". But to me, and many others, Evil and Wrong are just human mental constructs and the universe exists separate from human constructs - so they don't really exist outside of our heads.
Anyway, the question is "Do you want to accept reality/universe in it's raw form even though it could lead to a scary or miserable life?". None of us can completely do that, but at the very least we should hopefully understand which beliefs we're emotionally invested in and scrutinize those ones much much more.
Language is a big problem with these philosophical discussions and it's used wrong and abused constantly.
If your question was "How can I find happiness in a morally grey existence, where there is no universal right, wrong, or meaning - and it all ends with me being erased from existence?" then let me know if you ever find an answer to that - I'm seriously interested. Even if there is just one thought about this shit, that is both true and makes you happy - then let me know.
Sorry for the long rant.
tl;dr - The impacts of belief in something has no effect of whether that something actually exists or not. Moral Subjectivity FTW! There are no universal morals, rights, or wrongs. There is only empathy, laws, and consequences.