I had this surgery years ago. Your concern should not be about using your abs but about the internal healing as the ligaments that used to hold the uterus in place had been severed and are now someplace else.
I was able to return to cardiovascular exercise at my own pace within a week, but my doctor told me not to lift weight for about 6 to 8 weeks not to jeopardize the healing process. If you think you must teach, I would only talk people through exercises rather than participating in them. You will also feel that you need more rest, and the best you can do is to honor that need.
I wish you a speedy recovery.