This is very relatable for me. But I managed to overcome it.
Being born in a landlocked place, I had never been in any significantly large body of water before I got into scuba diving. My first dive was in an aquarium with sawfish and sand tiger sharks and I really enjoyed it, although I was a bit hesitant to splash in.
However, I was terrified of open water and the thought of diving in the sea made me super uneasy. Since I liked diving, I wanted to press on, so I took about 20 DSDs in pools in different dive shops and booked private lessons. I asked the instructors what I needed to be aware of diving in the sea and asked them to teach me all the necessary skills. Mind you, I was still scared of jumping in the deeper end of the pool, which was about 7 feet deep.
Then I went on a vacation and contacted this dive shop for a DSD in the sea. I loved it, but anxiety hit me for no reason at about 20 feet, and the rest of the dive I was just blowing through my air on the verge of freaking out.
What I say next is probably a bad idea and in no way do I recommend doing this.
I contacted DAN about my anxiety issue and asked for their opinion if I should try taking anti-anxiety medications before my dive to alleviate the stress. They recommended against it and advised me to seek medical help for my condition instead.
I did not particularly like their response, so I popped a clonopin the night before the dive, and, quite obviously I was very relaxed and the dive went smoothly.
I used that ”strategy” to do finish my OW course. I did the same for about 20 subsequent dives. Then I only popped a Xanax before the last dive out of the 3. Then I stopped doing that altogether. I did about 70 more dives “sober”, and barely had any anxiety.
Again, in retrospect, this does not sound safe at all, but that was my way. I did not have a chance to have a private instructor gradually condition me into diving, so, being in love with diving, I did what I could do. After that I did night dives on my own, did extremely murky dives in cold water, and I was ok. Still, I know anxiety is still there, but I learned to push through it, and one good way I came up with is occupying my mind with something - checking my spg, removing and putting my mask back on, checking my octo, "losing" and retrieving my reg. Just doing something that is anxiety-inducing on its own, but you know how to do.