I, too, would be concerned about someone diving with someone with a diagnosed panic disorder and a tendency to panic. Is it a diagnosed disorder, or are you assuming that is what it is based on past experiences? Have you had any therapy for it?
Such therapy for panic is not only possible, in many cases it can be highly successful. In many cases, it is simply a matter of changing breathing habits. When some people get into a stressful situation, they hold their breath without realizing it, or they do essentially the same thing by taking very shallow breaths. The result is that carbon dioxide builds up in their lungs, and that is the trigger that brings on the sense of panic. It is similar to sleep apnea, in which case sleepers for some reason stop breathing during their sleep until enough carbon dioxide builds up to make them awaken in a panic with their hearts pounding.
At the beginning of each class, I have students breathe with me under water to make sure they are breathing properly, especially exhaling properly to get rid of the carbon dioxide. It seems to help.
A while ago an instructor finished a class with a student who had a similar problem. She struggled with her mask work, and he did not feel comfortable passing her. We made a special session for her, and I taught it because I happened to be available when she was. We worked first on her breathing. I had her do a number of long, cleansing breaths before we descended in shallow water. We worked on basic mask clearing, with which she still struggled, until she was a champ at it. Then we took the mask off, etc. Then we went deeper. Then we worked on other stuff. It took her a very long time for the session (for which she paid extra, BTW), but it paid off. By the time we were done, she was swimming around in water with very poor visibility with no concerns, confidently removing and replacing her mask as she swam.
The first key to her success was her dedication. She had a really good reason to be certified, and she was not going to let this get in her way. The second key was the breathing. She learned to get rid of that carbon dioxide through deep breathing. The third key was patience. We knew she would eventually get there--we could not get frustrated by early failures. The fourth key was repetition of successful attempts. She could not be satisfied with getting it done the first time--she had to do it correctly over and over and over again.