My boss has a secret– could it get me fired?

My boss has a secret– could it get me fired?:
Dear Evil HR Lady,
I work at a Fortune 500 company. I recently found a scanned document that indicated that my vice president (female) and a peer (male) were buying a house together. I sent an email to my peer, Dave, telling him I had found the real estate doc and he should get his document off the network to protect their privacy.
I ended up emailing him the doc and deleting it from the company network drive to protect his privacy, and he thanked me in an email. I then later saw him and somewhat joked about him and the boss. He denied [they were having a relationship], said I was getting carried away and that I should not be reading private documents. I explained that all scanned-in docs are not named and you have to open all the docs to find your own doc. He said the real estate deal did not go through and that it proved nothing. I said don’t insult my intelligence and walked away.
I am afraid he may have told the VP I found out about them and that she may try to get rid of me. She recently fired my boss and another co-worker. She is a cold, ruthless woman and very capable of finding some reason to get me fired. She’s not that fond of me anyway, and I have had some problems at work. While I’ve met my goals, two clients complained about me, and I’ve recently made some noticeable mistakes.
Here’s my question: Should I go to HR and show them the proof of my coworkers’ relationship, since I have the document about them house-hunting together and the email Dave sent thanking me for deleting it? Should I tell HR that I feel that this VP may retaliate against me, or should I wait until she actually does? Would the proof I have of their relationship be enough if she tried to have me fired?
I really think that when my boss (who adored me) is gone in January, the VP will try and get rid of me because I know her secret and it would be embarrassing if it came out. Plus, she does not really like me anyway.
To read the answer, click here: My boss has a secret–could it get me fired?

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