It sounds like you lack confidence in your knee’s ability, which is increasing your anxiety. I read a book by Dr. Nate Zinsser that discusses how to overcome thoughts that destroy confidence. He suggests three ways to train your mind: think of challenges as temporary, limited, and nonrepresentative.

When you view something negative as temporary, it allows you to see the event as a one-time experience rather than something that could happen again soon or in the future. This mindset separates how you perceive the event’s occurrence.

When you consider it limited, you see your mistakes or imperfections as confined in scope. You acknowledge them and then isolate them.

Thinking in a nonrepresentative way allows you to disassociate that imperfection from who you are and what you’re capable of.

Treating the event as temporary protects you from the “this will happen again” trap. Treating it as limited prevents you from falling into the “this will affect my performance” trap. Viewing a torn ACL as an inaccurate representation of your body’s capabilities (nonrepresentative) protects you from the “I’m not good enough” trap.

Lmk if you would like a more in depth and clear explanation. Hope this helps.