My manager slept with my ex- boyfriend

So my ex boyfriend and I work at the same job and we started at the same time back in 2021. Within 5 months we began dating and everyone knew about it- including the owner of the business. Nobody cared as long as it didn’t interfere with business. My ex has had 3 promotions so far from supervisor to manager to now accountants payable. Since starting there my manager who is the (GM) became close friends with my ex, since they are close in age (she’s 37, he’s 40, I’m 25). She would go to him about work related issues because he’s very knowledgeable in the field and naturally she would also vent to him about her relationship problems. Her and I weren’t as close but we would still talk about things and up kept a cordial relationship. Now I was never insecure about their friendship but I would always get this ominous gut feeling about them. My ex boyfriend has a baby mother whom he shares 1 child with. I found out through the bm that they were still messing around which is why my ex and I have been in this toxic on and off relationship/situationship for 2 years. His defense was always that when we are broken up, he messes with his bm (which I learned was a lie because he did sleep with her TWICE while we were actually together). The manager knew everything that was going on and she saw how it emotionally affected me and my performance at work. My ex has a victim complex 🙄 he’s the type to think he’s NEVER wrong with anything. Somehow it was my fault that our relationship went downhill due to me breaking up with him. It stressed me out trying to mentally grasp how the turmoil of the relationship was my fault when in fact it was his blatant, disrespectful actions of lying and cheating…….. I truly don’t like to label people but by definition he has all the characteristics of a narcissist.

Fast forward to present time, I found out my manager had slept with my ex last month in March. This past Sunday night I was over his place and I randomly decided to get a snack out his cabinet. Right next to the snack I was reaching for, I saw this specific bag of candy that only my manager is known for eating at the job. I grabbed it and thought to myself since when he started eating this. In that very moment it was all the confirmation I needed to ask him if they ever slept together. He denied at first then confirmed it. He told me they hung out at his place with his roommate and then left to go back to her place where they later had sex. I was furious yet relieved that my intuition about them was correct.

*sidenote- I am leaving the job. I’ve found another and will be starting next month. Too much has happened and although I’m anxious about starting over, I’d rather have my peace of mind.