That is my thinking as well, that AJ would "side" with JH over Zach. Even if she would rather have been with Zach, JH obviously had custody and there would be no way I can imagine that JH would give up custody to Zach, especially under the circumstances. In a very real sense, JH was AJ's lifeline, and AJ would have had no choice in the matter, as has been pointed out above.
Additionally, I feel like, given the choice, AJ might rather have had Zach on her side than JH. On the other hand, I feel sure that she'd also rather have Zach as her enemy than JH, IYKWIM. As always, JMO.