Some people disagree with this train of thought. People will say, chemistry must grow between two people. That theory works for lots of people. However, with your question. A man that you haven't seen in 10 years.
Some people live a lifetime without knowing that type of passion.
Or if your chemistry with this man, grew over the time you spent together. Either way, I think you should at least take a break from your current relationship. It is just not fair, to your current flame. I'm not saying ends the relationship. Reflect, then decide who and what YOU really want in a true partner.