How honest should a breakup be?

“I met this great guy on Instagram who sent me a message because he thought I was cute. We hit it off and went on a few dates. I’m still in a long term relationship with a guy in California and I plan to break up. I’m trying to figure out if I should be honest with him and tell him about the dates or skip that part because it would make things worse…”
January 19, 2021
Pete KellyWeekdays 3-7PM