Question
is this a relative of the crepe mytrle,how tall will it get and any advice would be appreciated,thanks

Answer
No it is really not kin to Crepe myrtle. Wax myrtle is used as a living screen most of the time. It gets about 20-35 feet tall. Here is a web site that will give you more information. I have it behind my house and like its form and smell. http://www.sfrc.ufl.edu/4h/Wax_myrtle/waxmyrtl.htm