Quilters do prewash warm and natural batting to pre shrink. Cut a piece to fit your project from the roll, making it several inches larger to accommodate the shrinkage. Here are the instructions from the W&N web site:
https://warmcompany.com/products/war...n/warm-natural
As mentioned, do not agitate or spin. You can just soak in your top loader or use your laundry or bath tub.
So sorry for your loss.