A married man confessed his feelings towards me. What should I do?

Anonymous
I met this man 12 years ago, but because of our age difference (I was 17 and he was 27) he didn't feel comfortable asking me out. I had a huge crush on him back then. Well recently we crossed paths and he confessed how he's always cared for me, but just never had the guts to ask me out. He still really likes me but he also admits that he is happily married and has 3 kids. I really like him, but I told him I would never try and wreck his marriage. Should I continue being friends with him even though our chemistry is insane or should I back off?
A married man confessed his feelings towards me. What should I do?
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