Generally once something is epoxied it is permanent. You can try re-breaking the tail or cutting around things, but usually you live with the tail being out of square. I've gone through this once or twice on my own planes; you live and learn. If this was on a $1000+ airframe, I would probably remove the controls, remove some covering, and try cutting out or around the repaired area, rebuilding and restrengthening as necessary. It would be a lengthy and tedious process.

I would say live with the plane, and you will learn from now on to triple check the tail surfaces before and during the gluing process.