Unless you are planning to attempt driving it on the open ocean (Bad idea) which is not meant to operate and sea states might be extremely bad, you are definitely stressing out too much. Capsizing or flipping over tends to be from mostly reckless operator behavior, not water conditions on a lake.
These boats are specifically built to provide a smooth and stable towing experience for the person being pulled, and that means stable for the riders on the boat as well. There's nothing worse than the towing boat hitting rough wakes and it slowing down hard, then your tow rope bungies on you and throws you around when it picks up speed.
My advice, get informed from experienced boaters who have been boating for many many years. Believe me, most of us experienced boaters definitely won't mind giving you some tips and suggestions if you ask, either here or when you see them at the water.
Also, hands on experience in the various rituals of boating is extremely important. Unless you intend on only watching all the time (very boring), get out there and help in all areas with the boat. Cleaning, towing the boat, boat launching and recovery, and of course operating the boat in all situations. Doing this will help reduce or eliminate fears that come with inexperience on the water.
3rd Generation boater
15 years of experience
6 years of PWC experience.