I used to live in near-constant fear. I told myself that I didn't care anymore, just so the feelings of vulnerability wouldn't get to me. It was a stupid defense, but was all that I had at the time.
Apathy didn't help me, it wasn't who I was and I don't think that it ever worked to my advantage to think in this way.
I did get mental health treatment after I quit alcohol. The doctor put me on an antidepressant that was also an anti-anxiety medication. Alcohol no longer quenched the panic. It had stopped working for me.
The meds did stabilize me so I could listen, decide and act (mostly) appropriately, instead of always reacting to everything by first instinct.
It did take awhile to work on my brain chemistry. There was no instant relief. I had to change both my perceptions and behaviors. I had to retrain myself and choose a fresh identity from bits and scraps of the old Wally. I tried to hold on to the good bits.
Fear of losing irreplaceable things is still a very real fear, but I have to trust the Creator and Her plan for me while I am here.
I tell myself that if Plan A doesn't work, try a Plan B. You can't totally be prepared for every contingency, but it helps if you have a seamless compromise or back-up Plan in mind.
In the stress of today's world, having a 'fight or flight mode' really isn't such a bad thing. It just shouldn't consume us or have us in a constant state of war.
Breathe deeply.
Trust the system.
Best of luck to you.