Fighting?

[limey]

My partner and I used to fight like that. Depression is an unwelcome third party in a relationship, and it is very hard to be the understanding one when you SO says appalling things because of the depression: it is so easy to make hasty, dumb retorts which you will regret (as your SO will regret the things they said) later. BTDTGTTS.
We have also "refined" our fighting style and no longer grab each other (a rare occurrence in the first place), or break things. We still sometimes say hurtful things, but fights in general are much more infrequent than they used to be.
Is your GF getting treatment for the depression?
Have you read up on living with a depressed person?
Both of these things have helped us.
We haven't tried the joint counselling route because things are much more comfortable now, but we would certainly take that option if things worsened again.