Keep trying, you will find what works for you. My experience has been that my exercise CAN be broken into smaller chunks. I try to get in at least 15 minutes at a time, but for my whole weight loss journey, I exercised in the morning (pilates, yoga, fitness ball, stretchie band) and at night (cardio). I have the 10 minute solution DVD series and some days I literally worked out 10 minutes here, and 10 minutes there.
Since you have a Wii - I really like "My Fitness Coach" and I LOVE "Gold's Gym Cardio Workout". The shape boxing is an amazing workout - 30 minutes and I'm sweating up a storm! Both may be difficult, however if you have back issues. Have you tried the WATP videos? The nice thing about them is that you are in your home - so if your back starts to give you trouble, you can pause or stop and rest.
I say start where you can, and go from there. And, I respectfully disagree with your husband. You will see increased benefit from ANY attempts at moving more. They may not be dramatic at first - but sometimes we need to learn to walk, before we can run.
Make sure your eating is on track - the reality is that exercise is important, but to lose weight - getting your eating under control (making a plan and sticking to it) will affect the scale much more than exercise will.
It is much easier to eat 500 less calories a day, than it is to exercise off 500 calories (in my most humble opinion).
I like tracking my calories in Fitday - it is a great way to keep my honest and on track