One thing that I didn't take into account about the note until the arrest is that maybe the note is weird because it's written by a non-native English speaker? I don't know his level of fluency right now -- but depending on whether he's an immigrant and if so, how long ago he arrived here, his English might not have been perfect at that point. That might explain the unusual order of the words.
I used to be a proficient Spanish speaker, but I'm out of practice, so I plugged in "I'm not jealous stupid b****" into google translate. For what it's worth, what came back was, "No estoy celosa perra estúpida," which, translated back again literally with the words in order, "No I am jealous b*** stupid." "No I am" is the Spanish way of saying, "I'm not," so, "I'm not jealous b**** stupid" might be the way someone would write a note in English if they were a native Spanish speaker and translating from the Spanish to English.
What did the note say? Wasn't it, "I'm not jealous b**** stupid"