How do i tell her i dont want to date anymore?

Ive been talking with this girl online for a month and half now and shes just perfect, however its only been 5 months since ive broken up with my ex and after a while of dating this girl i feel drained as if all of my efforts have been drained in my last relationship not to mention that i still feel some resentment towards my ex and i fear that those feelings might resurface and ruin this.

I want to take some time off but i dont want her to feel that as if ive wasted her time or played her, i dont know how to break down to her.