What would you say if I didn't give back my engagement ring?
Is there a reason you're not giving it back?
Because I think I deserve it even if I did break up with him.
You might want to put yourself in his shoes. It's expected of you to return the ring if you are the one that broke up with him. It's the civil thing to do.
I'm not really comfortable with doing that.
Hey, I know breakups can be super awkward and uncomfortable, but it's also not right to keep the ring when you're no longer engaged to him. Other gifts are fine to keep but the reason behind an engagement ring is different, you know?