Hey Lily -
For starters, I agree with what's been said thus far about the self-prescribing - it's dangerous and Zoloft does tend to "poop-out" after a while - plus there are advances in medicines that there are newer meds out there.
As far as the anger, etc. - I know my husband tried the Prozac only to find out that it really made him lethargic and foggy. Each person reacts differently to meds. A family member who is on Zoloft and Adderall - wow, you know when they're not on it at all. While the person may tell you they are taking the medication, I think their behavior might be the clues as to whether they really are or not. There's an edginess to begin with then it's total lack of communication, lots of anger, frustration, and severe depression. It's not good.
Is there any way of convincing him to see a psychiatrist - perhaps someone he may even know? You are being put on the spot and being made to take responsibility for his actions. You are human too. Expecting you to always phrase things just so and so it won't irritate him? Sorry, but that's unrealistic in my book. He's got to take responsibility for his decisions, actions, and choices... not you.
While I'm not an advocate for divorce, there are times when it's necessary. Please feel free to PM me if you wish.
Many hugs,
Einna