Because I've seen this sort of thing happen several times in various contexts, I've long said that you should never write something you don't want to send. Not even as a joke that you plan to immediately delete. It's amazing how your brain will unexpectedly hit "send" instead of "delete."
You should be able to go into your sent folder. Click open the email in a new window (not auto-preview). Then File > message recall. It might be different depending on what you're using, but most of the time you look around the sent folder.