Humerus Injury - Please Help !!

Since 9 months, I was doing an excersize called the pullover. I did it on my bed with a heavy weight compared to my strength at that time. At the last repetition I was not able to pull it up, but I relaxed all my muscles and then contracted them to pull the dumbell but the result was that I bent my humerus bone. It was painful for a few hours but the pain was gone. After 3 months I was fighting with a huge guy in our school, I punched him and made him back off, but when I wanted to push him with my injured hand it bent again. And again since 2 months I was swimming with my friends and one of them started wrestling with me, and when I pushed him again the bone got bent. And today when I was playing with brother and I tried to grab and throw him with my injured hand, the bone bent again. I went to doctors and physical therapists and they said that there is nothing wrong with the bone, and a therapist told me that I have to do the same excersize that caused the injury but with lights weights. After the consecutive accidents I am feeling that I am very weak and I cant fight, and in the gym I feel that my humerus bone is going to get bent when I put heavy weights. Do you thin that the therapist is right? Do I have to go to surgery? Does anyone have any other suggestions? Any help would be appreciated and thanks...

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