Fantasy turned reality

I had an affair with teacher four years ago when I was in high school. He was 28 and I was 18. I started weekly tutoring sessions with him (because I sucked at maths) and we never studied during them, we always sat and talked. He told me about his wife and their new baby and he let it slip that they never had sex anymore. I’ve always had the student/teacher fantasy and got really aroused when he said this because I just started thinking about him bending me over and fucking me in the study room. We kept up these study sessions and I began touching his leg or brushing his hand, not thinking anything would happen. One day I put my hand high on his thigh as I leaned over to copy a problem from his computer and he let out a really loud gasp and pushed my hand away, I looked down and noticed he was really hard. 
I decided to push him back and get on my knees. He begged me to get up saying he wouldn’t be able to stop, I ended up sucking him off until he came. He fucked me on the table as he kept a hand over my mouth to keep me quiet. It was the hottest thing I have ever done. We met twice a week and fucked in that room every time. He ended up moving to another town half way through the year.