Not that I needed convincing but after listening to these videos I am 100% certain that the murder of Travis was premeditated and the motive was jealousy, pure and simple.
I'm not a psychopath but I have had a few situations where I broke up with a man I was madly (obsessively) in love with and they have immediately hooked up with someone else. There is no pain greater, at least to me, then seeing a man you love with another woman. It was unbearable and I became suicidal at the thought of him being with her, doing things with her. None of them ever married the woman but when JA says to Flores that she hadn't found anyone to marry yet but Travis had, I know without a doubt that on June 4, 2008 she believed that Travis's marriage to Mimi was a done deal and that was something she just couldn't bear. While I might have become suicidal I think JA became homicidal. There was just no way she was going to allow Travis marry another.
It's funny because the song "You Oughta Know" was my theme song. I played that full blast feeling every word. I believe that JA felt exactly the same way and her reaction was to eliminate the source of her pain.