Def go to your GP and ask if there is any coucilling available, probably not but it is worth having lodged on your record that you are obviously struggling with anxiety that is more than norm. Then if anything in the future was to happen it to get worse, the record is there. Mental health services are useless - not only useless, but heart hearted and denigrating - and I would advise staying away from secondary mental health services if at all possible, but there are some services available through primary care. Just, from bitter experience, avoid trying to tackle the problem with meds, they might provide short term relief but even the more benign ones will lead you down a road of mental fog that might not be apparent in the short term but will be a hindrance and a trap in the long run.
I think that appleHEAD has given you the best advice, both from the point if view of dealing with it in th moment and rooting it out so that it doesn't re occur - you need to process the things that are causing the anxiety. At least you are fairly sure if the cause - the reminder of mortality. The thing that strikes me most is that the fear largely stems from what would happen to those you leave behind. Find ways to reassure yourself that there are security nets in place, such as friends and family, that would rally round should worse come to worse. Plus that worst is unlikely to come to worst. Consciously think this through to yourself, and consciously think through how it can be mitigated.
And, it will probably pass. Keep the little pit of strength that we all gave inside us ploughing on through until such a time as things are easier, it can be done.
Keep the appreciation of life, keep planning ahead and appreciating the present, and just be mindful of finding ways to put little safety nets in place should worse come to worse - ie who would take care of your children, talk it through with those involved.
As for sleep, I have 2 tricks that doesn't seem to fit with the normal advice but works for me, not always but often. Relaxation techniques etc. do not work for me - that us when the pounding heart, hot sweats and racing thoughts and restlessness will drive through me.
Anxiety is your body's way of trying to get you alert and up and rolling to deal with problems
- so get up, if it comes, and use the moment to do some problem solving, if you can. Even if you dont get any really useful conclusion from it, the fact that you have put some effort in towards at least trying, ,might settle your subconscious enough that the matter is in hand, as it were. Roll with the anxieties attempt to raise hyper alert chemicals in your body and try yo put it to good use
This isnt always possible, especially when one is dead tired and too mushed to think well at all. You need to recognise when you are just not thinking clearly.
So the second trick, which I use every night to get to sleep, with more frequent success than not, which is a miracle after over a year of severe insomnia, is to use the heightened state of anxiety to attempt to hone one's powers of focus. Instead of trying to relax, I try to see the heightening of anxiety as an energy to harness to use to focus my mind, and so I use that to focus really hard on blanking my mind, or focussing on the word 'sleep' pictured in my mind. It isnt easy and does not always work and is quite a knack to get, takes some practice, but it certainly works better than trying relaxation per se. I have also found that really tensing my diaphragm and core muscles at the bottom of each breathe gives me a sense of having guts and inner pit of strength to deal with shit, that tension actually helps the rest of me, more outer muscles, to loose tension and let me free of some of the physical symptoms of anxiety and often gets me a better nights sleep
Might be a load of bollocks, but might help, hope it does!