advice please

Ok so Im engaged and was friends with this guy at work. We went out with each other along with our group of friends on the weekends. We would talk on breaks and while we were working. About 3 months ago I started backing off because I thought he was starting to have feelings for me. So I quit going out and I didn't really talk to him unless I had to. Well he told me that he had feelings for about 2 weeks later after I backed off. Then last night at work he came over to my car on lunch break and asked to talk to me and he kissed me. I pulled away but he pulled me back in. He told me that he thinks that he's in love with me. I told him I didn't feel the same way and he said he just wanted me to know then he left. Was it wrong that I even started talking to him in the first place