Whether you were "right" or not in breaking up with your boyfriend is a subjective matter and depends on your values, boundaries, and feelings in the situation.
What matters most is how you felt about his actions and what you believe is best for your emotional well-being and happiness. If his communication with his ex made you uncomfortable or caused trust issues, it is reasonable to consider ending the relationship if you believe it was the best decision for you.
Relationships can be complicated, and people have different perspectives on what is acceptable when it comes to communication with ex-partners. Some individuals are comfortable with their partners maintaining friendly communication with exes, while others may not be.
It's crucial to communicate openly and honestly with your partner about your feelings, concerns, and boundaries. If you have doubts or unresolved issues, talking things through with your partner can help clarify the situation. However, if you believe the trust has been broken irreparably, ending the relationship might be the best course of action for your emotional well-being.
Remember that your feelings are valid, and it's essential to prioritize your emotional health and happiness in any relationship. Trust, communication, and respect are vital components of a healthy and fulfilling partnership.