I’m sorry they broke things off with you. It can definitely feel a bit awkward if that person was the only member of the polycule you were dating, like they were or are now some sort of gatekeeper to being friends with the rest of the polycule. Are you finding it harder to spend time with others in the polycule in larger groups (with or without the person you seeing present) or in connecting and spending time in smaller groups or one on one with the others?
Let your haters be your satyrs at the bacchanalia of mediocrity.