I think an apology is in order.

I need to sincerely apologise. it was wrong of me to be satisfied with your injury. I know that things must be hard for you, because I've been through the same, and I shouldn't have laughed in your face.
nobody deserves what you had to go through over the weekend. not just the pain, but the accusation from your teammates who you thought would be supportive. or that lecture from your coach, who should've been proud of you for risking everything you had.
and no matter how much I disliked you, you don't deserve me laughing in your face, on top of everything.

I think you're really brave. you knew an injury was on it's way, but instead of taking the time off, you trained hard enough to forget the pain. your position in the team was something you weren't gonna give up easily, because you simply were the best. nobody can replace you on the team. I shouldn't have underestimated you.

I'm sorry, if there's anything I can do, let me know.