sex with a teacher

When I was in high school me and my teacher had feelings for eachother. We never did anything cause the fact I was under aged. I lost contact with him for a year. He contacted me to get back in touch with me, like friends, like old times. I would always hangout with him in school, during lunch and after schoo. He would give me so much great advice. We had so much trust in eachother. We hooked up months after I turned 18. Is that wrong? An 18 year old hooking up with a 35 year old.