I too had a bit of a falling out with some friends lately, so I know what its like. Whole mix of issues, and most of them my own. Real life issues, a really bad week in game, and some bad choices of words kind of set me off.
People said I was silly to take it even remotey seriously... comments like "relax, its just a game" or that it was childish to let online stuff get to me. Kind of true, but I see the first ten final fantasy titles as merely games. FFXI is a community, and for those that used IRC in the past know what that can be like.
Drama was frequent in IRC, even though there was no NM competition, no quests, no gear. Nothing "substantial" to fight over yet fights were numerous. It was like a linkshell without anything going on lol.. Yet back in the day I had friends fail out of school because of it being so addictive. The social interaction is quite important to some people.
Other players could care less... I often see players level up beyond everyone else in a LS and simply move on, never looking back. Race to end game and get leet gear... cant let a weaker LS hold them back. They are a pretty socially retarded lot, and if they notice you are depressed they immediately conclude it is because "you're just mad you didnt win the lot on "x" item or something..."... wow.
Anyhow,long story short... I know where you are at right now and I feel bad for you. These are real people in the game, real friends. Perfectly normal to be depressed when you lose them. A while back I too considered quitting for a number of reasons, decided to take a few weeks off, and have spent the last month trying to find what I'm looking for in the game.
So dont delete your account... give it some time if you can.