Seems like the discussion regarding security, while certainly appropriate given the current (and past) atmosphere regarding vulnerabilities and obvious fact that there really are people out to get you, doesn't really address the question that was asked which seemed to be a lot more personally directed than outwardly directed.
Happiness was the central point of that question. "WIll I be happier if I delete my Facebook account"?
And that is something I think each person has to decide for themselves. If you feel that the use of the social network platform in question is causing or contributing to your unhappiness then certainly it's something you need to consider, but be aware, once deleted that's it. You can't "undelete" your profile, get it back or contact FB saying "oops, that was an accident" just because you've changed your mind. If this is a new and possibly temporary consideration then I'd say to simply set everything aside for now, turn it all to extremely private and walk away until you've had time to see how it makes you feel without it.
If at some later point you decide that yes, I'm better off without it, move forward and delete it for good. If you feel as though you are having withdrawls, perhaps FURTHER consideration is needed as that would tend to indicate an unhealthy compulsion or addiction. If however you just feel like "man, I was just having a couple of bad days" and now you are seeing things more clearly, you at least still have the option to return to your normal interactions there and don't have to create a whole new account and start building your entire online social structure over from scratch.