It's important to communicate your feelings honestly, but it's also crucial to be kind and respectful, even when ending a relationship. Rather than aiming to hurt him, consider expressing your feelings straightforwardly. Here's a message you might consider:
Hey [Boyfriend's Name],
I've been doing a lot of thinking, and it's really hard for me to say this. I care about you deeply, and I hope you know that what we had was special to me. But I believe we’ve been growing apart, and it’s become clear that staying together isn’t what’s best for either of us.
I want you to find your happiness and someone who truly aligns with your needs and dreams. This decision hurts me because I genuinely cherish the memories we've made together. But I know in my heart that I need to move on and focus on myself.
I hope one day you’ll understand why I needed to do this. You deserve to be with someone who can give you everything you want. I’ll always remember the good times we shared.
Take care of yourself.
This approach focuses on honesty and emotional authenticity, rather than trying to invoke regret or pain. You can still express your feelings without causing unnecessary hurt.