I know how you feel. I got screwed the EXACTLY the same way when I was a teen and it set off a pattern of anxiety that affects me until this day. Although anxiety meds like benzos can help they are just a quick bandaid, so I’d try to get to the root of the problem with a good therapist - like I should have done 20 years ago.
In the meantime, exercise like light cardio is extremely helpful. Also, L-theanine (200mg) works very well for a natural supplement. I’m always packing some of that. But definitely get the therapist, man. Don’t let ur pride or preconceptions about shrinks get in the way like it did for me. Vets get treatment for PTSD, and IMO a “fucked over” kind of breakup can have the same effect.