I can't say I love you.

I can't say I love you to my bf, die from my last relationship. I never been so scared but that guy made me scared my new bf is so sweet and kind. I want to say I love you and tell him he makes my world shine when ever I see him. We always have these cute tickle fights. Which I never had before till this relationship. He doesn't know the full reason why my ex and I broke up I only told him part of it. I don't know what to do please I need some adult advice.