Welcome to forum!!! I too applaud your positivity, it takes a lot of character to keep your head up and be thankful for the little things, especially when life has thrown you a few "big" things. Wow, I'm inspired just reading your story. I know you only want to lose 70 pounds, but you still might check out the 100+ threads, nobody there cares about the exact number, we check in almost daily and are in this for the long haul. There are 2 of them, one in the Women's Only corner and the other is Unisex.
On the exercise front, have you considered swimming or water aerobics? That would be easy on your body and it burns a ton of calories, plus you probably won't break a bone if you fall in the water. The elliptical is great exercise too, but give yourself time to work up to it. I think I started out with it at like 2-3 minutes and then worked up a minute or two at a time until I could go for an hour. The elliptical works so well for me that we have one in our dining room. A stationary bike might also be something to try, set the seat up high and the resistance low at first and work up from there, you might even try the recumbent version which is a totally different workout from the upright. Another good, easy on the body workout is the rowing machine, it's great for core strengthening and none too shabby for the upper body and legs as well. Good luck honey.
Starting weight: 244.6 lbs. 10/01/09
Pounds lost: 80.6 lbs
Current weight: 164 lbs
Goal weight: 120 lbs
Weight to go: 44 lbs
Goal Date: 1/1/13