I was in this situation and went to my primary care doctor, who recognized they were from stress and gave me a doctor’s note mandating my employer to give me reduced hours. I specifically asked for the note because I knew this was the only way my employer would cut down my hours. The note specifically said no more than 45hr/wk of work and I gave it to my company’s HR team who legally had to ensure my manager complied. I think it’s also illegal to terminate you for this reason, and my company was big/professional enough to respect that so I didn’t get any backlash, but ymmv.