Hello bucketlist, for all the bad press it gets the internet can be your friend when you're in situations like these, no matter how alone in the world you feel, you can guarantee there will be someone out there who understands what you are going through, or in this case, a lot of people as you would have been reading! I am so glad you have decided to seek help, there's nothing worse than that feeling of energy slowly running out and the panic setting in.
You mentioned wanting to phone the ambulance in a panic, have you ever phoned a helpline before like beyond blue or the suicide call back service? I have done this before, and they are wonderful, its amazing what a calm voice can do to just bring the temperature down and help you think straight.
The other thing you mention is that you've been putting one foot in front of the other for too long, this is also a good technique for getting back to full strength... rather than being overwhelmed by so many things going on, to take things one day at a time and sometimes even one hour at a time while you start to get back on an even keel.
There is nothing to feel embarrassed about, I have said in another thread that meltdowns like this are like the brain's equivalent of a fuse going. It's a sign that you need support, and you have taken that step.
Who else have you got around you at the moment that you can confide in? Close friends, family?