I've been diagnosed with severe patella tendonitis in my right knee. What is the best way to recover?

Time vs surgery. Most can be treated nonoperatively with the use of rest and avoidance of painful activities such as knee extension machines, deep knee squats, lunges, step machine etc. Try therapy, antiinflammatories, ice and sometimes a knee sleeve. More recently anecdotal use of prp injections (also called stem cell injections) have been tried. Rarely, surgery is needed to clean the damaged tendon. See ortho.
Ice, rest, rehab. If this is truly acute tendonitis, ice, anti-inflammatories, and unloading with a patellar strap. Next, any faulty mechanics that may have led to the symptoms should be corrected. A sports med physician/physiatrist can determine if there is weakness of the core, or imbalance of the thigh or lower leg muscles. If chronic, new research has shown that it is not inflammatory, an treatment is differen.