I've hit the wall of despair

Sorry in advance, but this is going to be a fairly pessimistic post.

I've hit that point that I have named 'the wall of despair'.  I've only recently had a diagnosis, so in the past, when I hit this point, I end up circling down a dark hole that is very difficult to climb out of.

My 'ways' as they are often termed, have cost me so much over the years and it has taken a massive toll on my health and well-being at times.  My life has been spent working endlessly to fit in and navigate obstacle after obstacle.  I work hard so that I can have a successful career that helps take away the stresses of paying bills and having a roof over my head, but it all comes at a cost.  I become exhausted, overwhelmed, as well as being physically and mentally burnt out.

Recently I have had to cope with a number of changes and knee jerks at work and I don't know if it is directly related, but all aspects of life just seem totally overwhelming to me.  Every task that needs completing, bill that needs paying, food that needs prepping is one more thing pushing me closer to snapping.  The result is that I am constantly miserable, snappy, over sensitive and constantly fatigued.  My partner, bless him, tolerates it well, but it's not fair on either of us.

Today I reached that point which I try to avoid at all costs.  I am not an emotional person at all and rarely express emotion, however, today the flood gates opened where you go from nothing to feeling everything in full volume pure high definition.  This means my anxiety levels soar, my heart rate rises, I get pains in my chest and am on the verge of tears and the only way I know how to deal with it to stop me having a complete emotional breakdown, is to run away from whatever situation I am in.  As a result, I have walked out of the office today as I couldn't cope with it.

I've reached that point in my life where I am tired of constantly having to go round and round in this pattern.  I am good at my job, but me reacting in this way and making myself ill has cost me one career and I am starting to think I am hanging on to my current one by a thread.  Maybe I am not in-tune with what my body and mind is doing, but I always seem to lose when it comes to preventing hitting this stage.  When I get this bad, I become very emotional over everything, my anxiety levels go crazy and I become depressed.  I have been told countless times that life is tough, but you just have to get on with it, but when you are fighting against something that leaves you broken, how damaged do you have to become before you can fight no more?

The situation I now find myself in is feeling hopeless and vulnerable and I hate not having the answer that will solve it.

Have you had to have similar fights and what do you do to help you put the boxing gloves back on and go back into the ring?