Have you had a good cry yet? Privately, where noone can hear & then let it all out? Bawl until you give yourself a headache. Then have a good sleep, shower & do yourself up very nicely & go out for a walk and smile at people.
The trick w/heavy emotional things, I find, is to get out the strong emotion fully in a safe place. Then stop thinking about it. You may have to do this a few times if the stress was great, but over time, you'll need to do it less. DON'T let it build up so that you become obsessive thinking about it. Hope this helps.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh