I am sorry about your severe myopia. There is no generally accepted cure or therapy for high myopia.
Most patients are recommended just to monitor their vision for sudden changes which could indicate a retina tear or detachment, and to avoid high-contact sports where they could receive a hard blow to the head (which could lead to a retina detachment). Patients with high myopia usually have thinner retinas so the potential for damage is greater than person with normal vision.
For patients whose high myopia is caused by extremely 'long' eyes (long distance measured from the front of the eye to the retina at the back) there are a few doctors around the world who advocate surgery to reinforce the back of the outside of the eye, to try to slow further lengthening of the eyeball. In the US this is not a common practice; I am not sure where you are located so don't know if there is a doctor near you who might recommend this procedure.
If possible, you should see a retina specialist who can explain to you the warning signs of any trouble with your retina and what to do if you see a sudden change in your vision. Best of luck to you.