I had a one night stand with someone 25 years younger than me.Im 57,later found out the girl was pregnant.She admitted at the time I could be the father as well as her partner.Basically she had the child and I think shes mine,she says now it's her partners.Im convinced the child is mine and I'm tormented by this thought Do I have any choice but to accept this woman's insistence I'm not the father and move on?
Say you were to get a DNA test and the child did turn out to be yours, has she indicated she'd be willing to work something out if that were the case? It seems she's making it clear she doesn't want you involved with the child, but if you offer a DNA test how does she take it?
If the child turns out to be yours then I would imagine you have a legal right(and obligation) to be part of the childs life. But if any part of that means making things difficult for her current relationship, then I would personally wait a while. What made her have a one night stand with you? How long do you think her current relationship will last? I wouldn't make things too difficult right now as it could damage whatever they have with regards to stability in the childs life.
You don't really have any choice but to leave it and accept it. She doesn't want to know and doesn't want you involved. Yes, accept it and move on.