My old school isn't a school any more, but it's still there. Some years ago, when it was a sort of teaching resource centre, I had to take a bunch of my students there for a workshop. The lady on reception, when she heard it was my old school, showed me round the place.
I was apprehensive, because it too was the stuff of nightmares for me. It was heartening to see how much it had been altered inside. A cold, manky cloakroom made into a coffee bar and the classrooms carpeted and double-glazed. Some buildings had been demolished, others sold off and used as offices or whatever and - oh heaven - the gym was gone completely!!
It helped settle a lot of demons, and I've furthered that process by writing about it - actually setting a semi-autobiographical novel there.
I don't think you're nuts, Jock. School means as much to us if we hated it as much as if we loved it. The writing of it has actually helped me to achieve some closure on this part of my life and in fact has helped me to move on to something new.
Have a think about writing it out. Even if no-one else ever reads it, it might help you in the same way it's helped me.