Just to take another angle on it here. (because it's so easy to for mums netters to jump to the whole OW subject) So I'm trying to think if it was a man posing this same situation... what we may suggest.
I was in a lot of debt, for years... and I didn't tell my partner. It got to the point where I had literally run out of options, and I was so disgusted in myself I pushed my partner away, I turned into an utter bitch, flying off the handle at everything easily, stressing at the easiest decisions. I think I even had a similar situation to the broken drawer, only clothes ended up all over the house and in the bin due to a faulty washing machine.. anyways, I was a nightmare...
Finally all came to a head when my partner lost it, and finally told me what an utter cow I'd become... I broke down and explained the years of suffering I'd had to try and hide a bad situation from him (I didn't want to stress him out and in turn made life 10 times worse for us) I'm now with a debt management scheme, still skint, but my partner knows and I'm not trying to pretend I'm something I'm not anymore.
Like with your OH it was sudden and didn't last long. Luckily my OH was a better person than me and I was an utter idiot, we didn't have children involved (although we have one on the way now! :) ) and it all got resolved...
I'm not defending your partner (or myself) but sometimes it's not always worse case... I would look at ways of opening him up - as if he's already feeling bad about a situation, telling him about ending things may shut off completely something that could be resolved...
All speculation of course...