I’m not ready to say ‘I love you’

This is a confession I’ve been trying to fight against my stomach. I really did want to say it back to my current partner, but a part of me thought I would be lying. See, the guy I am dating right now; is perfect for me. He’s a gentleman who values me yet something is missing... I think what’s missing is that I’m still in love with my ex. This breaks me into a million pieces because I’m lying to my boyfriends face. My ex was manipulative, and didn’t treat me the way I deserved but we were young, and he was quite stupid.. he was the first guy I ever wanted a family with.. we were about to have a baby together, he said he was going to marry me. I really wanted that, and a part of me is afraid that I still want that with my ex.. I know this is wrong, but I’m deadly afraid that I am alone.. is there any advice someone can give me?