Fear not....you are truly not alone. As others have said, practice, practice, practice. Get out in the OW as often as you can. My first tri was a disaster.

As a kid I was hydrophobic to the point that I didn't learn to swim until late teens and "swim" was a poor term for the flailing I did. While I may have had miserable strokes if my head was in the water, I had (and still have) an awesome side stroke . On my first tri the cold water (pools were always warm) and the seaweed (arggghh...it is out to get me) and the other bodies (I'll drown! I just know it!) put me into a horrendous panic. I switched to side stroke and didn't calm down until near the end.

After that I vowed to get into OW as often as I could. Inland lakes early in the year and Lake Michigan when it warmed enough to tolerate. The freaking out does go away. And, when you finish that first OWS with a mass start...the feeling of accomplishment is greater than finishing the tri itself!