Right, so you used condoms with both men. So - you've already slept with the new boyfriend of 2 weeks.
I'm back to my point that exclusivity can be implied. Before OLD and the rise of the idea of an explicit exclusivity chat, I think most people would say dating + sex = expectation of exclusivity. And I believe that's still the same for most people, especially outside of OLD.
I think your boyfriend would think you cheated on him.
And as for "early days" - you posted calling him your BF, and you posted, full stop. If you thought you were still in a mutually expected open phase, you wouldn't have posted.
You cheated on the news guy, which was really shitty of you.
You're prepared to have affairs AGAIN.
Sort yourself out, before dragging other men into it 