It would put you in a bad position to soften the truth to avoid hurting the one you love today, so you're going to have to find a way to say what you need to say. However, because it feels emotionally perilous, you may convince yourself to postpone having this conversation; again, this isn't the right approach because it may not be fair to your partner to withhold something so important. The most powerful thing you could give your paramour is your authentic self, your honest heart and your true-blue feelings. Say it kindly. Say it gently. But do say it.