I have dealt with severe anxiety in the past. The understanding of death, the disenchantment with everything, and the anxiety which you describe, are all familiar experiences to me.
I am currently trying to tackle anxiety head on, so maybe we can stay in contact and share ideas.
Here are things which I have done in the past and still do in the present which I am absolutely certain help with my anxiety:
- Exercise. This is #1 in my trick book. I will bet you 100$ that if you do 30 minutes of cardio every day for two weeks, your anxiety will improve dramatically. That's not a lot, right?
- Walking in nature. This really tones down any excessive excitement, including anxiety.
- Feeling in the company of people you like. This may or may not be possible for you, depending on several factors.
I have also changed my diet significantly. Nowadays I never eat junk food. Everything I eat is cooked fresh and healthy. I find that the displeasure of eating badly is too strong for me to do anything different, but I actually have a bowel condition of some sort.
If you are experimenting with dieting, I can recomend that you start with a Paleo diet. I recomend the book "It starts with food" by Dallas and Melissa Hartwig. Very informative. Eventually you might also want to give a ketogenic diet a try. There are some posts on that in this forum.
As for using meditation... I have had different views on the matter at different times. I guess my current point of view could be put in the following way:
- Meditation has sometimes helped decreasing anxiety. Sometimes I would just pay attention to the breath, and I would calm down and go deep somewhere relaxed.
- But sometimes meditation has brought about an onset of anxiety! This has happened on various occasions, and in several different ways.
- However, nowadays I can stay relatively cool while experiencing anxiety so strong that it would have caused me to go run under the covers a few years back. I attribute this to meditation.
So while I wouldn't go so far as to recommend it outright, it can certainly be of some benefit, sometimes. That is my experience.
Other people claim it can bring an end to all kinds of anxiety and so on. That is not my experience (yet?). One thing I know for sure: meditation puts me in contact HEAD ON with the existential understanding of death --- the fleeting and unreliable nature of things. I continue doing meditation because it seems to practice certain skills which I value and wish to develop (concentration, mindfulness, equanimity, etc), but also in the hope that it will bring some resolution to my existential angst. But that didn't happen yet.
OK, that's it for the past. Now, I have done a 1 month retreat back in February-March, which was supposed to be longer, but had to be aborted because meditation brought on severe anxiety.
I came to the understanding, while meditating during several anxiety attacks, that the anxiety had something to do with the way I was breathing.
(This is highly experimental, bleeding-edge sort of thing for me, so all of the following could be highly innacurate.)
This has led me to a long internet search, and I eventually came to the practice of Butekyo, which is a form of breathing training meant to change (improve?) the way you breathe.
One nice thing about Butekyo is that it includes a fairly objective measurement of where you stand in relation to the practice. This is called the "control pause", and is measured by counting the ammount of time which you can comfortably hold your breath after a normal exhalation.
So here is a risky prediction on my part: I predict that your control pause is abnormally low, especially so during moments of high anxiety. In fact I would say no more than 10 seconds (my healthy friends have it in the 20-30s range). Would you care to measure it to see if my prediction was correct?
Here are instructions on how to measure your CP. Mine is currently 5 seconds. When I started measuring it was about 1 second!
Remember it is important that you must feel no effort or lack of breath after doing the breath hold. If you feel a lack of breath before you do it, that counts as zero

Anyway, I am currently exploring the Butekyo method and I should have more to report on that in a couple of months. Of course, it may still turn out to be a disappointment, so this is not a recommendation per se. But if you are interested, I have some nice ebooks explaining the method which I can send to you. (my email is bruno (dot) loff (at) gmail (dot) com)
In any case, take care and get well!