In addition to the excellent advice above, I would just add there are certain basic techniques that help many people turn unproductive stress into productive stress, the difference being with the former you feel out of control and the latter you feel more just energized.
One of the simplest is just to do some light exercise. A brisk walk or jog, biking, a swim, a little boxing practice, dancing, a sport you like, mow the lawn, whatever. It is an evolutionary/brain chemistry thing, but getting your body moving will help you regulate the stress reaction, intervening in the feedback cycle that can cause anxiety to spiral out of control.
All this is also in service of a cognitive framing that stress per se is not always bad, it is your body’s way of getting ready for action. The problem is in the modern world, action is less like to involve things like physically attacking prey, running from a predator, or so on. Of course there is still prey of a sort, like a nice juicy college offer, and predators, like AOs who might reject our kids, and so on. So our stress reaction is triggered, but we are not then involved in a physical struggle.
So there is often a mismatch between what our body is preparing for and what we are actually going to do. But recognizing this is not an inherently bad reaction, just mismatched a bit, can help reduce your overall anxiety level on its own. There is nothing wrong with you, it is a natural reaction.
And then giving your body some of the physical action it was looking for can finish off the job and leave you energized but not anxious.