Hi. I Have Been On Lexamil 10mg For About A

Hi.
I have been on Lexamil 10mg for about a year now and cope fine with it.
However, last night I suffered an incident while driving home - 4 guys were pushing me off the road and were swearing at me - they were intoxicated. I eventually stopped my car and stayed still and quiet until they drove off.
I burst into tears and felt a heatwave over my head and today I am still teary, anxious and feeling horrible. I am shaking still as I felt very threatened and terrorized. Nobody was around though so I didn't have help while they were bullying me.
I need to work full days and can't leave the office - major stress here as well. My pulse very fast.
What can you recommend I do or take to ease off the effects of the stress I suffered?
NB: I am on chronic meds for Hypertension.