Did I do the right thing?

I’m miserable today and I need advice.
Joe and I have been together nine years, not in the same house but spending most days together and travelling together for months at a time (we’re retired). It seemed to me - and everyone else - that we were a loving and happy couple. Ten months ago he announced that he’d planned a risky driving trip across Asia with an acquaintance, Cindy. He'd mentioned it to me once a month earlier, but we both knew I couldn’t do it; ever since a car accident years ago, Asia’s chaotic traffic terrifies me. He said the trip was on his bucket list and very important to him. Cindy would just be a companion, he admitted – not an experienced driver, navigator, or traveler, just a companion. Still, I was a good sport about it for months. Their trip starts in January 2017, so it’s been a hard year, watching them get closer as they made plans.

Then I learned they’d been dating secretly before they made their travel plan. He said that meant nothing.

In September Joe left an email open on his computer, a booking they'd made for three days in a single hotel room before the trip. He had promised they’d stay in separate rooms, and I'd naively believed him, so I was upset and angry. I reminded him how dangerous and destructive it would be to have a close relationship with two women. He said I was over-reacting.

Then a third guy volunteered to join them, so Joe changed the room to a triple, and I felt better.

Just a week ago he admitted that he and Cindy had booked a holiday in Asia alone for a week before the third guy arrived. He said it was to get over jet lag, and they’d stay in separate rooms, so it would be ok. But I checked his email (I’m only a little ashamed!) and found the truth: they’ve booked a single room at an expensive beach resort.

So after a lot of soul-searching, last night I told him - calmly, with no dramatics - that I knew about the single room, and combined with the lying and everything else, it was a deal-breaker. He gave frantic reassurances – they’re just friends, it was a misunderstanding, he'd made mistakes, etc. I said a romantic holiday with Cindy was disloyal to me and that sharing a bedroom with two women was not ok. Then I collected nine years worth of belongings, and left.

Today I alternate between feeling proud of myself and feeling devastated and unsure. Walking away seems like all I can do. But maybe there's another answer. I’d really appreciate advice.