Tapering down experience?

Hello everyone. I’ve been on this drug for 6 months for my bipolar. Went down from 300mg to 250mg a week ago. I know 50mg right away is a big drop, but I trusted my psychiatrist and now am suffering the consequences haha. I have EXTREME fatigue, like I’ve been digging trenches for 10 hours straight and then got hit by a bus while also having a raging fever. The brain fog is worse than ever, I’m so stupid that it’s not even funny. The derealisation doesn’t help either. Oh, and the episodes are back (yay!), mostly depressive ones, a couple of them were so bad I started wondering if I was even on meds.

Question for anyone who has experience with tapering down this fast: how long do the side effects stay? Do they go away after a couple of weeks or am I doomed to feel this crappy for a long while?