Protect Oreo’s life and help his leg

We live in an apartment on the third floor with our cat Oreo; he is a loving and energetic one-year-old cat. About 15 days ago, he fell off the balcony and broke a leg; I took him to the vet and did all I can to give him the best treatment.Now I have to cat-proof the windows and the balcony. We have eight windows plus the balcony where I have to install cat proof fences.

This happened before, but in that time he fell from another window onto a garden, and he didn't suffer any injuries. I thought it was a singular accident that won't happen again. But it did, and I feel so guilty and bad for him. I can't let it happen again, nor can I afford it. Now he is in a recovery period and is getting better with treatment, but he is still in shock, stressed, and fearful.

Last year was so tough on everyone emotionally and financially, and he has helped me and my family get through it with his loving personality and playfulness. I would be super grateful and really appreciate any help towards keeping him safe and continuing his treatment.