Good going Jough! And Mel! and everyone in change-for-the-better mode.
I say this because for a lot of people, the DECISION to make a serious lifestyle change is a hard thing to do, let alone the tough journey you have toward wellness.
I use that term because I think it's important to be sure to pay attention to your life's needs while you work on your physical health. So everyone else's advice is probably good (if not probably at some level conflicting) in terms of working toward decreasing your weight and raising your physical activity, my main advice is to be sure not to neglect you social, emotional, intellectual, vocational, and spritual needs while you concentrate on your very attention-dominating physical needs. ALL these things need to be attended to for your overall wellness.
It's impossible to overemphasize a doctor's role in this process too - sleep apnea can be life-threatening and orthopedic problems could result in huge weight-loss setbacks. Do you sleep with any kind of rig for the sleep apnea?
I have a friend in Akron who was in his 50s when he finally had bariatric surgery - he had many of the issues you describe but was probably close to 600 pounds at 5'10. I used to work with him and for a whole summer, drove him all over the state because his feet and legs had terrible sores that wouldn't heal. It was fun to hang out with him - he's funny, gregarious, and good at what he does - but it was also a real illustration of the worst outcomes of obesity over time.
The bariatric surgery was necessary in order to get his knees replaced. The knee replacements were necessary due to structural failure.
I think there is a good chance you are in a better position than he was - 20 years younger, less weight on your frame - so I think that you can do this without the surgeon.
I also have to say that I think that it is a pretty courageous thing to come out on a board like this and describe your situation. Using the term dying is not an easy thing to do but I think it describes only one potential outcome out of many, and I think you are a stubborn SOB and you won't let your situation get worse or destroy your quality of life. At least, that's how I see you.
Low impact exercise like swimming is excellent for everyone but especially people with bone and joint problems. Smells, if you are having joint pain or motion problems, you may be able to find a place that has an arthritis exercise class. Our Y does this. the Pool is always between 85 and 90 degrees and they go through some water excercises with just the water for resistance, but also since you are in water, less stress on your feet and legs. This might be good for you too, Jough.
Modified: finally read the whole of all the posts, Smells is right on and if they have the really highly heated pool, that is probably even better for you. Also, if your Y has aquajogging/water walking equipment, you might find that an interesting low-impact way to excercize as well.