hey Cody,
I really hope I can uplift you with my message.

This self-hate is resulted by thoughts you follow (just like your anxiety and depression). Somehow people are usually more attracted by the negative thoughts than the positive, and so we create (without knowing it) a cloud of negativity which affects everything we have. Someone could say you are a lovely person but your cloud would make you think : hell no that’s not true. The truth is : you are.
I’ve been bullied for 7years, I hated myself, I had dreams but kept saying yeah never going to happen, at some point it triggered anxiety and depression. But if I may say so, I’m somewhere grateful for this depression because it has opened my eyes to see my strenght and love myself for who I am and I destroyed that negative cloud from my mind.
If I can suggest for your case, I did auriculotherapy ( acupunctur for the ears) and thethahealing ( helped so much) and just talking about it.
You have a fiance, who certainly loves you and would love to see you bloom to the lovely person you are,just like your friends, he sees it in your eyes and it is time you see it too. it’s a state of mind, choose positive over negative, self-love over self-hate,.. it’s not about controlling the thoughts, because we have millions of them everyday, it’s about following the positive ones; acknowledge the bad but don’t follow it, reach for the positive thought.
It may sound completely insane what I’m saying but trust me it works. We are all awkward and unique.
Consider doing mindfulness and searching about positive vibes, yoga etc..

Just by switching your mindset from negative to positive, your day can change and so step by step your entire life will change, and later you will look back and say: waouw!
Start by smiling at yourself in the morning, give yourself positives vibes, avoid toxic people, do not compare yourself to others, each of us is different and unique, just be who you are.
For sports, if you fear people might look at you just remind yourself, they are here for the same reason with their own problems and insecurities, you are here for yourself, not for the others, so go there enjoy your course, and leave with fresh energy and before going to sleep, give yourself a positive vibe and sleep well!

You can do it! Never give up and smile!

Cheers!