Welcome! You've come to a great place where you will get support and discover that people really do understand what you're going through.
Are you exercising at all? I really encourage you to, as the commercial says, just do it. Buy a video or tape and do something at home, go for a walk, go to the gym, or whatever you want to do, but the hardest part is making yourself do it the first time. We're all here to urge you on, and we get very excited to hear about someone's progress, from taking that first step to reaching reaching goal weight and everything in between.
I'm just a year older than you, and what motivated me was health issues. I don't want to have that first heart attack--and I'm sure you don't want to have another!
Regarding your depression, many here have gone through the same thing. What helped me (besides medication) was 1) exercise, and 2) volunteer work. I didn't want to isolate anymore and I started volunteering at an animal shelter. That snowballed for me--I became a volunteer of the year, then was offered a job, then I started my own non-profit group. I don't think I ever would have done that if I hadn't been depressed so maybe depression was a good thing for me!
I look forward to hearing more from you--again, welcome!