Did I break up for the right reasons?

If it is truly the way you felt (becoming unhappy) and you were up front and honest with him about your reasoning, then you have nothing to worry about. Now if you just gave him some cop out reason for breaking up and no explanation, they you should feel bad because that is the shameful way to handle someone you once claimed to love. Anyway, having these feelings about your ex now could ruin your new relationship. You should be honest with your new bf, and then be honest with your ex about what you truly feel. Be honest to yourself and the both of them.