No good deed goes unpunished

I'm so frustrated right now.
I can't really even put it all into words.
Due to recent string of events and over-reactions on the part of others and mature adult decisions on my part, I've narrowed my local friends to a much smaller roster.
One of these remaining real friends is my former co-worker, T. She still works for the evil empire. Recently, she's been busy and stressed, and yesterday I bought her a cute little mug (on sale) at Starbucks and brought her the mug and lunch. I came to her office (my former office) to visit with her and have lunch. I checked in with the front desk, got a visitor pass, and went back to her studio area to eat and chat.
I hung out for a while with her, and also visited with S, her current boss, who is a new friend of mine (T introduced us about 2 months ago). It was well-intentioned social visit, with no malice.
I called T today, and she told me that the Operations Manager of her station stopped her, and told her he had heard that I was there visiting. She affirmed this, and then she was told that under no circumstances was I to be allowed to be in the "work areas" and studios.
Yesterday was the second time I've been there in the past month, and I was in no way being evil, malicious, sneaky, or any other thing. Both times I checked in with the front desk, got the visitors pass, and was escorted everywhere I went.
I wanted to visit two of my friends in their workplace... which just happens to be my old workplace.
I didn't leave that company on the best of terms, but I didn't leave on the worst. Due to mounting frustrations over my lack of advancement and respect, I left. Because they wouldn't give me any concessions on the non-compete, I quit without two weeks notice. And I worked in a non-related field and lived off savings for the duration of my 180-day non-compete. It has been over a year since I left, and over 6 months since my non-compete expired and I was allowed to work in my field again.
I know that my friends work for the "competition", but I know that individuals there (like T & S) are my friends.
The Ops Mgr that pulled T aside and gave her this warning is the co-host of the direct competition to the show I produce. He also hates the guys I work with, because they also left that group, albeit 15 months ago, and launched a show to compete with his.
I'm mad and sad about this whole thing. It sucks that I won't be able to visit T (though I do admit that I was told twice this morning by my current show that I do have "big brass ones" for even stepping foot over there). It sucks that she got admonished. It sucks more because I'm sure the Ops Mgr doesn't know that I know S (he's only been the boss there for a few months, and was not the boss I quit on), and so I'm sure he didn't get the lecture that T got. If S really thought my being there was a problem, I'm sure he would have told me to leave, get out, and not come back. He's too new there to ruffle that many feathers, and our friendship is too new to put his job in jeopardy over.
AAAAAARRRRRRRRGHHH!
I feel like shiznit about this whole thing, both for myself and T. When I quit over there last year, we stopped talking for months, to protect both of us. But time has passed, and it's not like I would sabotage equipment or steal trade secrets. I'm not that guy. I don't think people are bad people, and wouldn't ever do something that mean or stupid. I don't understand pranks, and I certainly wouldn't do anything that awful.

Heck, my Mardi Gras beads are still hanging on my old cubicle.

Oh, well, I need my nap. If you have any comments on this whole situation, please feel free to post them.
Pah!