Strongest:
* Devastated: Completely overwhelmed with grief or shock.
* Heartbroken: Overwhelmed with sorrow and grief.
* Beside oneself: In a state of extreme agitation or distress.
* Hysterical: Showing uncontrolled emotion or excitement.
* Frantic: Feeling or showing great anxiety or agitation.
* Agonized: Suffering intense physical or mental pain.
Moderate:
* Distressed: Experiencing worry, sorrow, or anxiety.
* Anguished: Feeling or showing extreme mental or physical suffering.
* Despondent: In low spirits from loss of hope or courage.
* Dismayed: Feeling disappointment or alarm.
* Worried: Feeling or showing anxiety or unease.
* Troubled: Experiencing difficulties or problems.
More neutral:
* Upset: Feeling disturbed or distressed.
* Concerned: Feeling or showing worry or anxiety.
* Stressed: Feeling or showing mental or emotional strain.
* Unsettled: Feeling uneasy or disturbed.
* Confused: Not understanding or being unclear about something.
The best synonym to use will depend on the specific context and the intensity of the emotion you want to convey.