On some level, your husband had to know that this moment might come, when your son is curious about his bio dad or wants to look him up. If you have already talked to your ex, you need to come clean with your husband. First of all, it's really terrible for your marriage to let this go on. Secondly, once your son sees his bio father, then what? Will you wait for HIM to tell your husband? The secrecy and deception will hurt your marriage. Tell your husband asap. Tell him the truth, that you located your ex to see if he was even interested, and he is. Reassure your husband that he is a key man in your son's life but that your son has the inevitable questions about his beginnings. You will have to decide whether to tell your husband that you have always known where your ex is, or whether you will gloss over that part of it. But further deception from this point out will hurt your marriage a lot more than telling him now. He has a right to know. If you know he will be "furious" then you need to figure out why - furious at you for deceiving him, or for finding your ex, or for making arrangements without his knowledge. Then deal with that. If you have concerns about how this is going to go, find some counseling (therapist, clergy member, whatever). Your husband has a right to his feelings too. If he's awesome and your 3 years together have been wonderful, then that is an important foundation.