You were told that you weren't supposed to contact her.
Doesn't matter if that's fair or legal or whatever. It's simply a bad idea to "bring up the HR issue" when walking home alone. And your conversation was probably very short mostly because it was extremely uncomfortable for her.
Shortly after that you're wondering what's happening now. Instead of asking HR, you're texting your co-worker again!
Then there's lots and lots of petty squabbling about semantics and exact meanings of terms in your "restrictions" (where you actually do have a point or two – but it simply doesn't matter. You're not supposed to talk to her!).
Yes, you totally contacted her again and again, but "it was a groupchat!". That's totally different. Not.
If you ever get into such a situation again: take HR's warnings seriously. The second after you stepped out of the first meeting was the second you should have realized "I'm in big trouble, deservedly or not, I need professional help."
Maybe a lawyer, maybe a friend, maybe even a therapist. What do I know? But you definitely did not need those knee-jerk reactions. "Hey, let's find a loophole where I can convince myself it's okay to contact her".