Damn. Impressive, mate.
As for cold tub soaks-- I find it easier than anticipated, but hope that is a result of focused preparation. I take a good 20 minutes of breathing first until I can trigger tinnitus and feel the energy flowing in my circulatory system. I like to enter cold when my ears are ringing.
Keep breathing. Get out when you want. Getting out when the needles stop and the pain goes away is a good point. (like 1-3 minutes?) I had my wife present the first time I dunked myself in an ice bath simply because it was kind of scary. Like-- "Am I going to have a heart attack? I've never done this before."
I think it's reasonable to be scared of it. There is very little in our daily lives that says getting into an ice bath is probably a good idea. It's not until after we undergo the training and conversion of our metabolism & brown fat that the cold begins to call us.
And don't expect any miracles. I think simply getting in, not dying, and learning you can still function enough to get yourself out is probably an accomplishment for the first time.
Good luck. Slow and steady. Play the long game.