Hi and welcome. I suggest going to your doctor, and possibly being referred to a weight loss specialist so as to not harm yourself in the process. He will know your health problems and how to approach losing weight for you.
There are so many fad diets, others that that take off pounds only to have them reappear, and some downright dangerous to the individual; they are out to make money off of you.
Last but not least, make sure this is something you can continue the remainder of your life; it takes real commitment. Up and down weight loss is probably more dangerous to you than than none at all. Also consider a sensible approach to Cardio exercise and light weight training at a gym possibly assisted by a trainer.
Many heath insurances also offer programs best suited for their members; check into it, and may God bless you to find the proper course of therapy to live a long and happy life.