She quite possibly was never in love with you. Her being older than you is also a red flag. Women don’t want to be in a relationship with a guy as he’s starting his adult life and trying to build himself up… They want to date the guy who already finished that. I’m betting she checked herself out of the relationship a long time ago and kept you around as a meal ticket until she could finally monkey-branch to another guy. The words “open relationship” are also a major red flag as it indicates she’s looking for a guy to replace you but wants to string you along during that process. She is for the streets and you should never speak to her again.