This isn't ethical polyamory, and omg are they misusing egalitarian here. (True non-hierarchical polyamory means you equally weight your relationships, but NOT that you can do what you want without the consent of your existing partners).

This isn't even polyamory, because he isn't seeking consent, and is using "polyamory" as an excuse to take advantage of women and cheat. You weren't being dramatic and you did the right thing getting out.