Lots of (good) practical advises for the day to day in this thread, but no mentions of Katabasis. Here's my take on the emotional side:

Stop the medication. Ride the way down and then back up. Cry your heart out, feel that pain, don't hide from it. It's a process, and has even a greek name:

https://en.wikipedia.org/wiki/Katabasis

You are on your journey into the underworld and darkness. Face it and you'll come out stronger on the other side. Humans have endured much harder times. You are more resilient than you think.

Your days will start to improve little by little. Little glimmers of light here and there until you start leaving the bad times behind

I went through a separation 5 years ago after 12y together, no meds, just counseling. Not sure if your case is separation or death, cause I haven't gone through the latter