To answer the original question, normally Prozac is a good choice for that depression, but for split personality, you might need to move on up to the anti-psychotics. May I suggest Haldol? Perhaps a "cocktail" that includes both, with a Valium chaser... you'll be, um, *yourself* in no time at all!
Stay away from the herbals, as they vary so much in potency and prevent reliable dosing. Consider counseling as well, and in your case, I'm sure you could get a group rate!
Be well!
[:P]