I feel like, while in an ideal world we would be able to disclose mental / physical disabilities to our employers, a lot of work places make it unsafe for you to do so. Even if they have a policy in place that supports that, when they actually have that information I feel like it can at times still be used as collateral. I think it’s a unique job where it’s totally safe to disclose that information, unfortunately.

Tbh, your boss doesn’t have to know all the details of your inner life. I think it is acceptable to tell him you are sick right now, and I think it would be acceptable for you to respond to his message about your work performance (during a time you have stated you are out for sickness) with a reminder that… you’re sick. He doesn’t need to know why or what. Tell him it’s the flu or something tbh.

In any scenario like this (esp if it’s something corporate and very top - down), I would always suggest doing the thing that will protect you and keep your best interest at heart. Often times this is keeping your personal information personal and doing what you need to do to get your needs met in the best way you can.