You want one of two things gypsum and or sand. The gypsum will soften it up pretty quick. The sand amends it so it becomes more soil like. Somewhere back in the dark ages, I read that soil is made up of three components: clay, sand & biomatter.
You are a very smart woman karen. I planted stuff and then asked what to do about my clay so now I'm trying to work around my plants
in tiny increaments to amend the clay lol. It's an adventure.
Are you going to do a compost pile to help get the biomatter into the clay mix? It will help.