i have a major dilemma...

so maybe its the lack of sex in my life, but i feel like my way of thinking is wrong right now :( I've had a girlfriend for 2 and a half years, and we haven't had legitimate sex in the longest time. like its so awkward. sometimes when I'm alone (like right now), i start thinking about the way sex was with my 2 of my exes. i don't get off to it or anything, but i just think about how HOT it was...so INTENSE. both my exes were cheaters and liars, and i don't have any feelings for them...but if i were in a room alone with either of them (or both), i think i would just go at it and not care. i love my girlfriend, and having these thoughts just sucks. does this make me a terrible person? because i definitely feel like one :(