Why can't they go over her place to spend the night, where you won't have to see it? I know that I probably wouldn't be able to stand having an ex around so much right after a break-up, especially if I was already jealous of their time with my partner.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.