Congrats, Hill Slug! It takes a lot of guts to step in the water that first time, and a lot of people do panic. A friend of mine had a really hard time getting going her first tri in open water - she'd been in open water before but never really learned to swim-swim properly until the months leading up to the event, and it was daunting, the feeling of panic overwhelming. She did finish the race and did sign up for another race the next year.

Even if you don't do another tri, the lessons you learned will obviously benefit you as a person, and that's the real goal. You accomplished something, you did something for the first time, and you stuck with it. Way to go.