Certainly your life is not over, and neither is Squash’s. Everyone’s life has phases. Sometimes it’s this phase in life, sometimes it’s that phase. It’s still life, and it’s normal for us all to do different things with our horses at different times in their and our lives. If you were made permanently lame, would Squash’s life be over? Of course not. She would just adjust to you being in a different phase, riding-wise. So, that’s what you will do. You will keep loving Squash outside of riding her, and you will eventually find the right riding horse for this phase of your life. You probably didn’t really expect to find another perfect horse right away; it’s normal for it to take awhile.
Take the pressure off yourself, as it does us no favors to be trapped by some rigid pre-conceived expectation. Smooch on Squash and continue to have a friendly curiosity about other horses.