Is it right to talk to someone you once loved?

I had an argument with my partner last night and I thought it was done. It got me thinking about looking up people I used to have in my life.
I searched all manner of places for some people but I couldn't find them. But one I did find I text and they replied back. What's worse is that that person was my perfect match and we used to get on like a house on fire. The problem was that we were on different sides of the pond and she was living with someone when we talked.
Even so we spoke on video call 6 hrs a day for months. Then he found out and we stopped talking. Life eventually went on and 9 years passed. Now she does follow me on Insta but we didn't have any communication. But last night she did respond via another social media platform to me and I wonder if it is possible to rekindle something? Or is it just an impossible dream.
Maybe me going through an old laptop earlier in the week and seeing pictures of her started me thinking. All my current partner wanted me to do was get rid of pictures relating to my second marriage. Maybe it stirred something?