So if the law remains in effect and Paul does call it our school master and Christ says to say (teach) other wise is enough to make one last in the Kingdom of heaven, then what does fulfill mean?
"...then what does fulfill mean?"
It is a covenant thing. It is like making the last payment on a purchase agreement. It is fulfilled.
Heck, according to Dictionary.com:
1. to carry out, or bring to realization, as a prophecy or promise.
2. to perform or do, as duty; obey or follow, as commands.
3. to satisfy (requirements, obligations, etc.): a book that fulfills a long-felt need.
4. to bring to an end; finish or complete, as a period of time: He felt that life was over when one had fulfilled his threescore years and ten.