IS IT WRONG TO HAVE FEELINGS FOR HIM?

i’m a senior in high school and back in the fall one of the most popular/good looking guys in my grade slid up on my snapchat story and started a streak with me. he’s had a girlfriend who is also from my school since last spring maybe. anyways, we started talking little by little as he initiated. although the conversations always seemed to take a turn and we ended up talking about sex. at first, he wanted to know how far i’ve gone, how far i would go, if i masturbated, and so on. but then he started asking me questions like “length or girth” or “slow or fast?” the questions got super personal to the point where i felt uncomfortable so i confronted him about it. i told him that i wouldn’t talk to him about sex like this all the time because of his girlfriend, that he could go talk to her about it. he apologized and laid off it for a while but soon enough weeks later he was back into it. we still have a snapchat streak of about 70 days but i’ve had to ask him several times to lay off the sexual conversations. it’s even gotten to the point of him telling me that he’s home alone, asking what i’m doing, or him telling me that he thinks blondes are sexy (i am blonde, his gf is not.) i don’t want to get stuck in the middle of his relationship but at the same time is it wrong to mess around with a guy you find attractive if the two of you just talk about sex? i enjoy talking to him but don’t want to get in the middle. what do you think his intentions are? could he be into me or am i just being used to give him a turn on? also, HOW DO I DEAL WITH HIM? should i end the streak and cut him off completely?! sorry this is so confusing. i need help!!!