Navigating complex emotions in situations like this can be challenging. Here are some suggestions for what you might say to the guy:
Express your feelings: Be honest and open about how his actions are affecting you. Let him know that it's difficult for you to hear him constantly talking about his ex-girlfriend, especially since you've already broken up with her.
Set boundaries: If you feel uncomfortable discussing his ex or hearing about his feelings for her, kindly ask him to avoid bringing up those topics around you. Explain that you need some space to move on and heal from your own past relationship.
Encourage closure: Suggest to him that it might be helpful to find closure from his previous relationship. Encourage him to focus on his current relationship and appreciate the person he is dating now.
Be supportive: While it's essential to communicate your own feelings, also try to be understanding and supportive of his emotions. He might be going through a tough time, and talking about it could be his way of processing his feelings.
Encourage self-reflection: Encourage him to reflect on why he's still holding onto feelings for someone who has moved on. Help him recognize that dwelling on the past might hinder the growth of his current relationship.
Suggest seeking help: If his fixation on his ex continues to affect him or your relationship with him, recommend that he seeks support from friends, family, or even a therapist. Professional guidance can be valuable in gaining perspective and moving forward.
Focus on your well-being: Lastly, remember to prioritize your own emotional well-being. If the situation becomes too difficult for you to handle, it's okay to take a step back and give yourself space to heal.
Ultimately, how you approach the conversation will depend on your relationship with him and how comfortable you feel discussing these matters. Be compassionate and considerate, both towards him and yourself.