That is an excellent letter, Honey!!!
I also agree on not giving more than a month since you are dealing with a jerk!!
I know my co-worker let us know way early when he was leaving-- but he had to because we all knew he got into graduate school in another state!! Same with the co-worker before him- he got into Law School-- so we knew months in advance. But the guy who left before the Law School guy got another job and gave two weeks!!! (I work as a youth employment counselor and for some odd reason the other employment counselor position is like a revolving door!! I have been here for three years and the longest anyone else was here was 18 months!! haha)
I would say your case is similar to my two co-workers who moved away-- but since this guy sounds like a jerk-- I would not give him more than a months notice!!! The only reason I agree with a month and not 2 weeks is because then you can leave on good terms by helping find and train a replacement-- and you need more than 2 weeks to do that!! Good Luck!!
ETA: I found this on a legal website-- so I am guessing this mean you can give a bad job reference-- but he could not lie or bring up anything about you if not directly asked--
My former employer is sabotaging my job efforts by giving negative job references to prospective employers. Can I sue for libel?
Generally, statements made by a former employer to inquiries from a prospective employer can be made without fear of being sued later. However, protection will be lost if there are any ancillary suggestions, inferences, innuendoes, etc. that lead a prospective employer to attach a different meaning to what is said or to believe something misleading or untruthful about the employee. The difficulty is proving that the statements were inaccurate and wrong.