Panic attacks are not normal. They come on for no apparent reason. Fortunately, it doesn't sound like you had one. It sounds to me like you became frightened for a valid reason and that fear grew into panic (or perhaps merely near panic, your post isn't that clear).
Let's examine diving in general, your situation in particular and what you can do to correct your problem. You can correct your problem, but simply diving more is likely to merely hide the problem where it could easily creep up on you unexpectly in the future.
People do not live in the water. We breathe air, not water. When we breathe underwater, we drown. I know this, you know this everyone knows this. The idea of breathing underwater scares us. It should. This fear was driven home for you when you accidentally swallowed a large amount of salt water, felt like you were drowning. After an experience like that, you have to expect to be on edge on a dive.
We generally overcome this fear as we learn to dive and become comfortable with our skill as divers. This is not automatic. We have to learn specific skills. We have to become quite good at them. We have to know we're good at them. We have to practice them.
A critical skill that should be second nature to every diver is one which many (most?) never truly master. That skill is no mask breathing. Every diver should be able to breathe as well underwater without a mask as with one. That only comes from practice. I often hear divers comment that they never practice no mask breathing or that they are not comfortable with no mask breathing. You've told us that no mask breathing is an issue for you because to aborted a dive due to a loose mask. Not to worry, this is a fairly easy skill to master.
Go to a pool. You only need 3 things at the pool at this point. 1. Mask 2. Snorkel 3. Weight belt with weight.
At no point will you leave the shallow end of the pool.
Take your snorkel off your mask and put on your weight belt. With your mask on the pool deck, your snorkel in your hand and your weight belt on, get into the shallow end of the pool. You should be where when you stand you are no deeper than chest deep, waist deep is even better. Put your snorkel in your mouth and breathe from it. Now, bend over and breathe through your snorkel while you dip your face into the water. If you are comfortable, stay awhile until you feel natural. If you have difficulty, think about drinking through a straw while you practice the excercise. Remember, you can always stand up straight to end the excercise at any time. If you need to, you can slowly build up your time until you feel comfortable.
Next, practice dropping underwater, allowing the snorkel to flood and coming up to blast it clear, leaving your face in the water. Continue until you are comfortable
At this point, you have accomplished three important things.
1. You lowered your anxiety level by working in a no risk (shallow) environment.
2. You became an expert in no mask breathing.
3. You know you can breathe with a flooded mask.
Now, put your snorkel down and pick up your mask. Put it on and drop down to your knees. Break the seal just enough to allow a small amount of water in. Clear the mask. Do not pull out on the bottom, merely push in on the top while looking up. The biggest mistake most people make is not looking up. The second most common mistake people make is not exhaling through their nose. Keep your mouth closed. Repeat this until you are comfortable. Don't forget to stand up and catch your breath between clearings. Now, increase the amount of water you allow into the mask to about ¼ flooded. When you are comfortable with that level, move to ½, then to a fully flooded mask. When you've reached the point you can clear it easily every time, see how many times you can clear it on one breath. After you are at this point, clearing your mask will be easy. You will have reached it in a step by step manner that was easy to accomplish.
Remember, you can always stand up if you feel uncomfortable.
This will solve your problem. Next time you feel your mask is too loose, you'll adjust it underwater. If you have to take it off to adjust it, that won't be a big deal, although most tighten with a tug on the strap.
After you are back in the water, make it a point to take off your mask and practice no mask breathing on every dive. Soon, people will be commenting that they wished they were as comfortable in the water as you are.
Finally, any time you feel frightened about anything, concentrate on making sure you are taking slow deep breaths. Slow deep breaths will clear your head and allow you to think about what ever is disturbing you allowing you to think of a solution.
You can do this. Believe in yourself. I believe in you.
