How to not get wound up in it all?

I made some off-hand comment today about my DH's therapy, and of course he used it as a jumping off place to direct all his anger at me. I'm working from home today (he is doing some fix-it projects), and he's been storming around here. This is pretty much par for the course for the last 6-8 months. Something sets him off, he storms around, he insists on engaging in some kind of "fight" that is really just him berating and badgering me about all I am doing wrong, and then eventually it calms down. I am so over it. What I can't seem to do, however, is disengage from it enough to just go on about my day and do the things I need to do without being emotionally affected. How do you do that? I can't concentrate. And I'm just sitting here trying to work wondering when he's going to storm into the room next to just throw his bad mood at me. Anyone have any strategies to share?