Nearly 30 years ago, I may have gotten my girlfriend at that time pregnant, and she gave birth to a child. I was young and ashamed and didn't want to have anything to do with her when I found out. Later on, I got married to another girlfriend, and I was ashamed to tell her about the situation. Nobody knows about it -- even in my family.
Ten years ago, I saw my ex-girlfriend and the kid who was a teenager for the first time. I have lost contact with them since then. This situation keeps me overwhelmed and ashamed all the time, I don't know what to do.
Even though I am a newborn Christian, I always asked myself how to handle this matter and how to have a peaceful mind. My wife and I have a good relationship, and we both are Christians. I am afraid if she finds this out, it would alter our relationship.
Please help. Would God forgive me for not taking care of my supposed daughter and not telling my wife? I am so overwhelmed and ashamed.
Yes, you made numerous mistakes in your past. Because you refused to take responsibility for your actions, you locked yourself up in inaction all these years. You never found out if you were the sperm donor for the child. I don't know if your ex-girlfriend ever said you sired the child or not. Legally, if she thought you were the father, she could have filed to have child payments made by you, but it sounds like she never pressed the issue and raised the child herself.
You can't change the past. You can't take on responsibility for a child who is now an adult.
Does the child know you might be the sperm donor? Was she introduced to you as your child when you met her ten years ago? If that is so, then it is possible that she might contact you in the future and I would recommend that you tell your wife so that it is not a surprise in the future.
If your ex-girlfriend never brought the issue up after all these years, I doubt she is going to do so now. If you and she are the only ones who know and you are not certain, then I would suggest that it is best to leave the past buried. If the subject of past sins comes up privately between you and her, then you might consider mentioning that you committed fornication when you were young and a child might have resulted, but you are unsure if you were the sperm donor. If you do talk about it, then mention that you are embarrassed about how you behaved back then and the shame of what you did kept you from mentioning it to your wife.
"My brethren, if any among you strays from the truth and one turns him back, let him know that he who turns a sinner from the error of his way will save his soul from death and will cover a multitude of sins" (James 5:19-20).