I was wondering if anyone could offer any advice on how to cope when you find yourself in the middle of an emotional crisis?

Over these past few weeks I've been having a bit of a tough time. Different things every fews day just annoying and frustrating me. These have been ranging from, double booking when making plans so I've had to let down a friend, pressure at work, generally being tired, forgetting my bank card, I have a food allergy and a 'safe' restaurant we often go to was fully booked so we tried somewhere new but that meant the only safe choice was a salad for me.
Annoyances from my ex husband regarding child care and maintenance money, ex husband cut off our internet (was still in his name so instead of changing it to mine he cancelled the subscription) these are just a few things.

Yes I know that individually they may seem small but these have been dripping through my life and last night I just lost it.

I have a bad back so asked my partner to rub some deep heat cream on it to help me, the tube was empty and that was the last straw for me.
I totally lashed out and blamed him, I was upset, crying, angry and in some pain from my back. It all just erupted over the cream being empty and I was shaking and crying.

That for me was an emotional crisis. That's my definition.
After a while I calmed down and be helped me and was understanding.

So I have a few questions;

1. How do people cope when they find themselves in the middle of an emotional crisis. What do you do to ground yourself and actually think rationally.

2. How do people recognise the signs BEFORE this happens to prevent it in the first place?

All advice help and tips welcome