guy adviceee

Ok let me give you some background info. My co worker and i have been very close since i started working. We work together alone all the time and we constantly tease eachother and laugh and i noticed i started to really like him. Everyone tells me they think he has a thing for me because he treats me different than everyone else. The only problem was i had a boyfriend. Now i dont and hes completely aware and hes acting even more different ( good different) texting me outside of work and stuff. So how should i hint to him that i have a thing for him without scaring him away and coming straight out and saying it? how could i flirt with him to get him to realize it but not enough to sound desperate?