I think numbness usually happens *because* there's pretty strong emotions underneath. The mind doesn't feel ready to cope with all the emotions, so it tries to shut down emotionally. To me, this numbness is usually what I experience when I dissociate, if feelings become too strong, I sometimes suddenly switch to a state where I feel nothing at all. Yet, like you, I know that there's feelings underneath. I think you made a good point about it protecting you from yourself. Your brain knows that this is a extraordinary situation for you and that the feelings would be too much to cope with right now, so it tries to shut those feelings down and be numb instead.

Dissociation is a way of coping, though not the best one. It's a mechanism that should protect you from getting too hurt, and it's good at that, but ideally coping would mean working with the feelings.
As for how to stop, you probably have heard of the basics, try to do grounding exercises, mindfulness... but don't push yourself too much, in your shoes I'd probably try to get by until I have a session and do these things there, with L present. Then when the dissociation goes away and the strong feelings hit you, there's somebody there to help you cope with them in a good way.