To answer your initial question - it could become alienation - if she starts filling your son's head with derogatory stuff about you.
So at the next hearing you want to be asking for a recital that says "Neither parent will make derogatory remarks about the other parent to the children". It's a guide marker rather than easy to make happen, but it could help at the next stage that this is on record.
This will all be sorted when you get to the end of the court process. Along the way it will be like a rollercoaster sometimes as your ex will be fighting everything along the way. But it can settle down completely once a final order is made. And the final order needs to be watertight and worded really clearly. Many of us have fallen foul of vague, badly worded orders. So we help each other out with that with tips for order wording