How to let someone down nicely?

Okay so basically i’ve been writing and i found an editor who offered to edit my writing for free and we eventually got into a talking stage. While i did like him i recently got back in touch with someone i used to really like and i think i still have feelings for him..? I would really love to stay friends with my editor cause he’s a very cool person but I don’t want to lead him on. I feel horrible but i just dont feel its morally okay to not say anything. We don’t talk incredibly much because he’s busy alot of the time and kind of dry but i’d just love some advice on how to tell him without hurting his feelings?