Name changed.
My DP was in a relationship for 2 years as a teenager. They split up when he was 17/18 as he had a one night stand with someone else and he admitted it to her straight away but she split up with him and blocked him, he knew he deserved it so he didn't try and contact her or her friends again.
About 2 months ago, his mum told him she saw his ex and that her son looks like him, he brushed it off at the time. A few weeks after that, he searched her name on Facebook and found her profile, it was public so he saw the child and he does look like DP. He brushed it off again but I could tell he was thinking about it a lot so he went on her profile and found out the child was about 8, and we worked it out that he was with his ex, 9 months before the child was born. He sent her a message but not a friend request so she didn't see it. This week, he decided to send her friend request and she accepted it and saw the message. She told him that he is the father but to leave them alone as he already has a dad and it'll just confuse him and it's his own fault that he can't be involved, but he didn't even know she was pregnant! DP doesn't know what to do now, he doesn't know whether to leave his son as he seems happy and he probably believes the other man is his father but he also wants to meet his son.
Any advice will be appreciated