HOW CAN I FIX MY STATEMENT I GAVE TO THE POLICE SO AN INNOCENT GUY DOESNT GO TO PRISON, I LIED.

ME AND MY EX BOYFRIEND HAD BEEN GOING THROUGH ALOT THIS PAST YEAR. AND BEING ON DRUGS AND NOT BEING ABLE TO HANDLE THEM DOESNT MAKE OUR SITUATION ANY BETTER. AND WE BOTH HAVE HAD OUR SYCHO MOMENTS WEATHER IT WAS TAKING ANGER OUT ON EACH OTHER OR ON THINGS. BUT THIS CERTAIN TIME WE WERE GOIN THROUGH IT BAD AND MORE ME NOT SO MUCH HIM JUST COULDNT HANDLE OR TAKE IT ANYMORE. AND BECUZ I ALREADY NEW MY FAMILY NEW HOW BAD OUR FIGHTS GET TIME TO TIME AND NOING HE DOES HAV A OLD ASSAULT CHARGE ON HIS RECORD I WANTD TO HURT HIM LIK I WAS HURTING CUZ HE WOULDNT BELEIVE ME OVER HIS FRIEND. I NEW THE EXACT WAY TO PUT HIM IN JAIL. SO I FOUGHT N FOUGH WITH HIM AND FINALLY I STARTED TO GET PHYSICAL N I SLAMMED MY FOR HEAD INTO HIS HEAD N IT SPLIT MY HEAD OPEN N BEING NOBODY SEEN OR HEARD US I RAN FROM HIM N THE COPS CAME N I TOLD THEM THAT HE DID THIS ALL TO ME AND I SAID HE WAS TRYIN TO GET ME INTO THE TRUCK BUT I RAN FROM HIM.CUZ NOW THEY WANT TO GIVE HIM 9YRS N HES INNOCENT. WAT CAN I DO PLEASE?