Help explaining something to mother, please help!!?

Ok long story short, I injured my right leg and knee in volleyball when I was 12 in 2006. And since then till this day I have been I gues you could say jumping hurdles over this issue. Mistreated by doctors and misdiagnosed. But I finally went to my first physical thapy day in 2008, but that same day we had 2 deaths in the family that hit us hard so we ignored my problem for awhile and I dint do therapy after all. Now after all these years I finally have a name for what's wrong with me which I'm so glad, it's patellar tendinitis. There small tears in the main ligament that connects your knee to your leg. Ok now I went to my first evaluation for physical therapy after 3 yrs, like 2 weeks ago. But since I found a name for what's wrong with me, everything changed. Like I'm satisfied now, like I don't care if my knee gets better. I'm happy with just a name, and I guess I feel I've been functioning with this injury for like 7 years and it's the only way I know how to live and function, and I don't wanna change anything. I wanna live with my injury, but my problem is I'm 17 and the only child so the parents are a challenge. My dads clueless, so thts not a prob but my mother is the main prob. I've tried to explain to her how I feel and what I want, and she basically called me crazy and blew it off like nothing happened which I hate. And now she scheduled my first physical therapy day without my consent, but I'm planning on having a one on one talk with the physical therapist about my decision, but I'm scared that I'm gonna lose my mothers love, and the bond we have. And I can't bare to lose that, it's all I have. I'm scared she's gonna hate me forever. Need a little advice on this issue please, any opinions would help a lot PLEASE!!!