well he might be bipolar, and an AD (anti-depressant) such as Zoloft, taken by a bipolar person who does not simultaneously take mood stabilizing and/or antipsychotic drugs, can lead to mania.

mind racing 100 miles a minute
cannot concentrate
too irritable (says you are picking on him)
cannot remember things is similar to cannot concentrate

suggests a MANIA coming, and no, it is not petty - you need him to report all of those things to his p-doc (psychiatrist - whoever prescribed ZOLOFT to your husband) on MONDAY - just after the weekend is over with. It can cause very serious trouble if left unattended. Do not delay.

If bipolar is ruled out, then the symptoms of a changed personality could be attributed to Zoloft, and then he either needs a different AD or just off AD's.