It is too bad that your visit to the guild was a bad experience. I formed a very lovely quilting group where we share ideas and help each other, no formality just great fun and fellowship.
I love the Cathedral Window Quilt, have made two and taught making it numerous times (all for free to keep the tradition alive). I have done the outside edges two different ways, one I roll back the white squares like you are doing to form a faux border and the other way is to fold the window squares in half to form a triangle window. I teach an easy setting of the squares but yours is looking great! Keep going, it will be worth all the effort.