I'm feel like the worst person

Well...I'm with my BF since 1 month and a half and...after some feelings came, everythings disapeared.Now, I like him more like a really close friend/sex friend than my BF, and I'm attracted by another man I met recently.The other guy and me turn around each other and we'll probably become sex friend, but I don't want to do anything while I still with my BF ('cause I don't want to cheat on him).But well, that's hard to break up...I know he will suffer, 'cause he love me, so I don't know how to do it :/The worst is, when I try to convince me to break up, he cutely send me snap with big smile because the red heart emoji is back between us, that make thing even harder.I don't know what to do and I feel like I'm a big douchebag.TL;DR : Like my BF, not like a BF, don't know how to break up to get thing more serious with a future sex friend and feeling guilty about it