First, MTV has a lengthy biography that's worth reading. Also, I'd like to challenge a few enduring mistruths about him, because as crazy as he was in his later years, I think he came by it honestly.
(1) Lupus is a debilitating disease that can be devastatingly painful, which explains the meds.
(2) Vitiligo causes depigmentation of his skin, which explains the self-consciousness about his appearance.
(3) He broke his nose in 1979 and the rhinoplasty to repair it wasn't entirely successful and required a second one, and then a third one... This doesn't explain all 13-or-so plastic surgeries, but it explains how it all began.
(4) Every time he made an appearance -- no matter when or where -- people would scream and faint and bang on his vehicle. (If people screamed and fainted every time they saw me, I'd be paranoid too. Just saying.)
In the long run, I prefer to remember Michael Jackson is one of the most talented entertainers of all time. Yes, he was different, but if you were the most recognizable living person on the planet, you would be a bit different too.