Dealing with 'failure' thoughts while in crash/splat mode

I've recently been thinking about how I deal with thoughts of "I'm such a failure, I can't do this/I can't cope." when I'm in crash/splat mode.

When I'm on my period the associated hormonal levels always cause me to splat - barely able to get out of bed, I might manage to write a short email in the 5 minutes after surfacing from a nap, but will quickly return to non-functioning. A similar thing happens during heatwaves.

 
During times like this I routinely feel like a complete failure: I can't run a business, or cope with running my home, and feel like I just want to give up on everything because it is all too much anyway.

What I found is that telling myself that "You aren't a failure, of course you can run your business/home etc" actually had a negative effect. It brought guilt. And pressure. And "In that case, I should be doing things that....I can't do".

My current strategy, that works for me in this specific kind of situation, is to separate the feelings: Group A: I am a complete failure. Group B: I can't do this, I can't run my business, I can't run my home.

And then address the thoughts like like this:

Group A 'complete failure' thoughts: "Yes, I feel like that, but it's actually nonsense, so I'm going to focus on managing this crash - and doing that is a big success in itself. I will come out of the other side and be able to do more again in due course."
Group B 'I can't' thoughts: "True. Right now, I can't do those things. And the reason is: I'm hormonal (or insert other key factor triggering the crash). That will pass, and I will be able to run my business and home again soon. A few days out to recover is really constructive, and it's totally ok that I can't do those things for now. They will wait for another day."

This way I can relax, and acknowledge current limits. I can be constructive within them, instead of panicking that the limits exist.

(Obviously, this doesn't apply to long term changes. But for those short term down-turns - the hangovers from doing too much for a special occasion or emergency, the times I'm fighting an infection or trying to cope with hormones or a heat wave or other temporarily exhausting factor - I have found it very helpful.)