Walter and jbd are right, scuba isn't for everyone and you should not do it to please someone else. The discover scuba idea is a good one but DO NOT take hubby along! You don't need the extra pressure of him standing there hoping you like it. Heck, you don't even have to tell him you're going.
I've been diving for 9 years now. I'm claustrophobic but with a little work I've found the confines of a wet suit, hood and mask to be comforting rather than scary. You'll never catch me in a cave, that's asking too much. You know your personal limits and you know deep down whether you want to conquer the fears you have. You'll have to look inside yourself and try to see WHY you have the fears you have.
A fear of sharks and big fish may simply be the result of too much t.v. The odds of being struck by lightning are better than the odds of being bitten by a shark. I went on my first shark dive last summer and to tell you the honest truth it was pretty boring. They came, they took turns eating the bait and they left when the bait was gone. Never gave us a second look. The majority of the fish you will see are going to be the "smaller" ones and they are fascinating to watch.
What scares you about large open areas of water? There are dive sites that don't involve such big areas if you don't mind diving water that's a little colder. That's a pleasant experience too.
Water in your ears, well, that's something you can get used to in the tub or local swimming pool. Just take it slow if you want to conquer that one.
Diving opens part of the world to you that the majority of people never get to see anywhere but on t.v. There are a lot of myths out there, if you're getting diving advice from a non-diver don't believe it until you check here because odds are they have no clue what they are talking about.
Was I ever scared? Sure! You can't come up with anything that I haven't already freaked out about! I had a very patient instructor and that's what you'll need too if you REALLY want to be a diver. Don't be afraid to shop around if the instructor you get seems to treat your fears lightly, a good instructor will help you get over them. And feel free to ask any questions here, there are lots of people on the board who have ideas about how to overcome different fears. No question is considered stupid.
Remember, do this for yourself, not for someone else. It's ok if you try it and hate it, diving isn't for everyone.
My motto is: "Try everything 3 times before you decide you don't like it" This goes for everything from diving to eating broccoli. The first time you try something it's really scary because you have little or no idea about what it's like. The second time you try it you've got enough experience under your belt to know what to expect and you will start to notice exactly how you feel about the activity, food, etc. The third time you know exactly what's going on, now is the time for you to decide whether this is for you. If I hadn't given diving 3 tries I wouldn't be doing it now.
Best of luck on your decision, let us know what you decide to do! We're here to help! We'll still like you if you decide not to do it!
Ber