your boyfriend really messed up... if he was truly thoughtful the first time would have been to make sure you had a good first experience, not to feel manipulated into him being allowed to fuck someone else. I hope this was just a moment of weekness, but for this to work he needs to recognize that you are a first timer and he needs to honor your process and need to take it slow.
He totally cut off any trust and respect he had for you. If I was you I would say that the relationship is to stay closed for the next 6 months to re establish trust and then after that, to start doing soft swap same room or some girl/girl stuff if that's what you're into. If he's not into that, I think you guys have a difficult decision ahead of you.