I agree that he needs to be in his daughter’s life and take care of her. It was a one night stand OP’s friend had a long time ago. Do you really think it was love he felt when he slept with her? If it doesn’t make him happy, I don’t think that would be the best for the kid. It would be better to have amicable seperated parents rather than ones that fight all the time.
He knows that the child is his. He’s been checking up periodically on the mother’s social media to see pictures of the child. If the child looks like him and was born a year after they slept together, the child is probably his. I doubt he would be jumping to conclusions and be this stressed if he wasn’t sure the child was his.
The child is his and he needs to own up and take some responsibility. If he wants to be a coward, that’s his choice. The least he can do is pay child support. If he refuses to do that, she needs to drag his name through the water and sue him to oblivion. It’s disgusting of you to say that he shouldn’t even do the minimum.