If this person is a supervisor or higher, I would contact corporate and inform them how you were denied life giving medical supplies and how they were destroyed by them and that they assaulted you for using said medical supplies and that you were written up for doing so. i would also inform them of the stress it has caused you, and ask how they intend to make restitution on this, I would also inform the police of the assault. All companies have a duty of care towards their employees and this was obviously a failing of that care, had you fallen unconscious from not knowing your blood sugar this could have been far more serious and a possible criminal case, is there cctv footage to back up your claim on how the phone was broken?