how do you know you’re in love? Good or bad

I dated this guy for a while, we eventually broke up, and i was hurt. I understand that’s a natural feeling, but we hooked up a few weeks ago and the unusual traits are beginning to cross my mind. I obviously care about him, if I didn’t I wouldn’t even bother. I can’t explain it very well, but obviously when we were together I was comfortable with him, and I cared for him. The problem struck me after we hooked up the second time around. I had moved on completely, I didn’t have any feelings for him anymore - or at least I thought I didn’t, and I just wanted to hook up and be done with it. When I get around him I change, it’s so fucking hard to explain, but his scent, his hands, it all intoxicates me like a drug. We hooked up, talked a little bit, and by the end of it it was fine. But right now (and I have no one to blame but myself) I am in so much goddamn pain I can’t express it. I hate him, but I want him, so fucking bad, like it’s a drug. Now I could very well just be an emotionally unstable sociopath, but I’m not a very attached person, physically or emotionally, to human beings. I don’t get overly invested in things I know won’t last, so I can’t imagine why the fuck I have so many feelings inside over him when he treats me like I’m nothing. why I’m wasting my energy and feelings. I can’t call it love because I have no idea what the fuck that actually feels like. But what the hell is it? Is it toxic love? Is it some sort of fucked up mind game I’m putting myself through? someone please try and explain it to me