Well it's a very fucked up thing you did. And you best believe that he's gonna remember it until he dies. And specially whenever you guys have a big disagreement from now on. But I don't blame you. Because it's an honest mistake. And since you already told him that he is an "accident", the proper thing you can do now is be a parent to your son. Tell him that you meant he was a surprise and not a tragedy. Tell him that he was a blessing to you and not a curse. Tell him that he taught you love and not hate. Tell him that you have nostalgia about him, not regret. Just be a parent. No gifts. No gimmicks. No money. Don't give nothing else, but your love to that kid because he needs it. Trust me. That's all he fucking needs. You need to make sure that he will never be depressed over the fact that he was an "accident". Because the anger he has now will turn into a beluef that he isn't worth your parenthood. You need to solve this now because if you don't, it could dominate his life and make him think his existence is flawed. If my advice doesn't help then do sth else. Just make sure that kid is not gonna feel an outsider in your house.