I tried to get over this person, i met this person 26 years ago in high school, we've been close friend all?

these years, i've express my love for this person but they it's only puppy love. I still after that heartbreaking response that i decided to just keep the friendship, at least i'll have that! life went on and we visit each other and there is a strong attraction between us that even my sister seen. When me and this person are alone there are physical flirtation and it turns me on. help me!