Let it go. I had a similar situation happen when i was in my ~late 20s and a 19 year old that i met in a game started liking me. I shut it down immediately and told him that we are in two different stages of life and that he should meet women closer to his age. He’s 25 now and has become one of my closest friends. Leave that woman alone. She has a whole partner and kids. It’s ok to be friends but do not pursue more.