Feelings are hard to keep in

I always thought I knew what "love" was like. I had a boyfriend for 5 years and thought I loved him. Turns out I was completely wrong. The guy I am currently seeing I have come to realize I love him. I have never felt so strongly for someone before and it is overwhelming. I want to tell him so bad how I feel but we aren't even in a relationship yet because he isn't ready for one at the moment but we have been seeing each other for the last 8 months. I feel like not telling him is the right thing to do at the moment but whenever I am with him the feelings I have are so strong that at any moment I feel as though the words are going to come right out of my mouth whether I want him to know or not. I am so scared of what he would do or say if I ever did this by accident.