Guys, Help. What is happening?

I'm best friends with a guy, I've known him for over 10 years. When we first met we were both in relationships, but he told me he liked me. Nothing came of it. We became really good friends and super close. He has always been in and out of relationships. Then he became single and I was, I realised I had much deeper feelings for him. So we ended up having sex (this was a few years ago) we never ended up together then, we actually stopped talking for a few months. But after that our friendship carried on. Fast forward to today and he is married, I haven't spoken to him for a couple of years, but we have now became friends again. This time he is more open to what he wants and he wants to have sex with me again. And I feel like a fool, I do like him, but he's married. Have we ever been friends? Could he have more feelings for me other than just sex?
Guys, Help. What is happening?
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