H coming today, what do I do when he asks how I am

[NikB]

Do your best to stay upbeat. In fact instead of "fine" I'd say "Great!" and vaguely refer to some fun plans you have coming up (you have some, right?). Such as... "Great, can't wait to get out of town this weekend." Or "Great, so excited to catch up with old friends this weekend" or whatever fits. Don't make something up... but refer vaguely to something you're excited about.

When he says he's a mess, act like it's a coworker or neighbor or something. Be sympathetic, validate - "I'm sorry you're feeling that way" - don't offer suggestions or advice.

All the DR basics...

Good luck.