I'm so sorry to hear of your pain...I can't relate to your current pain, but I can relate to your frustration.
I've had chronic patella instability for years, with recurrent subluxations in both knees. In spite of this, I fell in love with ballroom dancing and was actually training for a competition that's in October this year. Unfortunately, even though I was diligently doing proactive physio, my knees had other plans. On August 17th (just over a month ago) I had my first full dislocation... the left kneecap stayed out for more than 4 hours while I sat in tears at the ER without painkillers, and now the kneecap doesn't want to stay put so physio is a real challenge. I thought the pain alone was bad enough, but then I discovered all the things I wasn't going to be able to do for a while, maybe never again... I won't go into detail on those since I don't want to take this thread off topic.
I really feel for you. I'm still at the stage after my injury where I'm just trying to get ROM back. It feels humiliating to be unable to do a simple thing like bend my leg when just a short time ago I was so active. There's a good chance I too will be going for MPFL reconstruction and maybe even trochleoplasty.
Maybe I'm not the right person to comment, but right now you're at the beginning of your recovery. It feels terrible now, but it will get better! As I'm sure you know, moving around is really important right now even though it seems impossible. This part of your recovery will probably be the hardest, but afterwards you'll be stronger than ever! That's what I'm telling myself at least, even if it seems delusional at times.