Yep...it happens - that's why we call it a melt down. Here's what I tend to do
Take a breath, get some 'down time' and dont do anything about IT (whatever it was) right now today.
When the tears dry, the smoke clears etc...turn to your support and 'talk it out' if necessary, figure out what needs to be done (if anything)
as in apologies or explanations (if needed)
dont waste an inordinate amount of time feeling guilty - sometimes we just get overwhelmed
and this is what happens.If you have 'triggers' , make a serious note to try avoiding them for future reference, but accept that it might not be possible.
if there is ANY way possible try to find the humor in it? sometimes something like that is there, lurking in the background
plan to eat breakfast more often and stuff like that