sexual harrassment on facebook and the law?

[Robert]

so, i got a bit stupid and basically created a false facebook account and have been messaging an ex work colleague. i hold her responsible for forcing me out of my job essentially. i started by sending her a picture of a penis asking if she wanted some of this. i then continued to send her a constant stream of what could be construed as sexual messages, some of which are quite provocative. this individual is the sort to report it to the police, especially if she thinks it could be myself. all of this was done in a jocular way and essentially i just wanted a way to 'get back at her' however petty this may be. i realize that this was a very stupid and childish thing to do. can anyone advise me what may happen to me if it is to be reported to the police. i am fully aware that i can be traced by my ip address.
i know i have been extremely stupid but any advice would be greatly apreciated