OK take a deep breath.
Lets talk about it clearly.
You lose a game, that one things. You lose to your friend, that two things. You bring that two things to yourself, it is 3 now.
You lose a game because you are out of shape, it is fine, you just not lucky this time, not every man detest girls with some weight and you can be better.
You lose to your friend, it is betrayal, your friend was disgusting.
And it is your fault that all bad things happen.
It is mix of 3-4 bad feeling together.
A man is not at any fault, i'm not bias, anyone can pic what is good for themself. He did not made any promise, he just not ok with you and go for your friend after one date.
You can forgive your friend but not forget her disgusting behave.
You call feel miserable as you are but do not forget that everything you experience this time can be change next time.
Keep going, you can be beautiful the way you are but dont think about it like a fault of you not doing the way your friend have been done. How she makeup or dress is not the problem, the problem is she have been try harder than you to be beautiful. this world give reward for who trying and trying the right way.
You can be beautiful the way you are, you dont have to do just like any girl in order to be beautiful, and you can be more beautiful than any girl out there, but you have to change the way of thinking, to be a fatty lady is not characteristic of anybody, it is just a lazy.
This story is separate in 2 part, your fault and your bitch friend fault.
You just confuse and dump a part of your fault to be all your friend fault.
Learn it and do not do it again.
Keep trying, i'm rooting for you.