OWS...facing my fears

I had a loooong time fear of deep, open water and got into triathlon in part to see if it would help me get over it, and it has. To be totally honest, the swim on my first tri was a real struggle, not through lack of ability or fitness, but because of anxiety (about the water, the race in general) and I experienced that tightness in the chest and ended up side-stroking 3/4 of the swim. Funnily enough, my next race could not have gone any smoother, I knew going in that my run and bike were very strong and that, if I just cruised the swim I could still put in a good time. Once you are able to just focus on yourself and your race I think you will find that many other external factors start to fade. If at all possible, completely ignore the 'sprint' start, you'll find that a number of people who go out hard will end up fading and if you can just get into a comfortable pace that you have practiced, you'll end up passing many of them in the second half.
The next best advice I ever got was to do a proper warmup before the event, like get up in the morning and dress a lot warmer than you usually would, keep your body temperature high (without sweating like a maniac), do a good run (or bike, or whatever else works) warmup and then, if at all possible, get a few minutes of swimming in before the start. This helps you get used to the water temp and you wont be gasping as much as you might otherwise (although 68 degrees is balmy compared to the SF bay, which is around 54 at the moment!). It'll also loosen up your shoulders, the wetsuit will start doing its job (i.e. keeping you warm) and you'll be used to having your head/face in the water.

Good luck, I'm sure you'll crush it

Thanks ollie....great advice and helpful to hear others have overcome the anxiety of ows. No wetsuit allowed for the one the end of July...the one 2 weeks before does but it is a shorter swim and I think getting used to a wetsuit this close might be too much...plus I would have to rent one.  Will likely buy one next year if I keep doing tris.  I am going to try and get out in the lake 8-10 times in the next 2 weeks ...hopefully this will help.

I too had real problems with the OWS, although the race was in the river rather than the sea, I still freaked because of the jellyfish, the wildlife in the sand, the pelicans, the depth etc so know where you're coming from.  I just kept at it, forcing myself to swim there once a week until I felt comfortable.  I swam until I felt the panic, then stopped and started when I felt calm again.  Every time, the distances I swam got further until, after fewer weeks than I thought it would take, I could do the distance without stopping.  Keep at it and I'm sure you'll get there.