What Should I Do?? Does He Just Want Sex?

When I turned 18 my mom allowed me to have my first boyfriend. I had no experience at all. After a few moths of dating we had sex and he stopped talking to me the next day. AT the time he was 23 and I was still 18. I cried for days and I begged him to go back with me but he was already dating his Neighbor. Then soon after his OTHER Neighbor.
I was pretty upset but I was deeply in love. When he ended both of his relationship we went back together. I know it was pretty stupid of my part after what he did to me. Anyways we got engaged but I truly never forgive him for cheating on me. Our lives together were miserable we always fought. Two years later as of now I am 20. And I decided to mom back home with my mom, but on a way we are still dating.
I meet this amazing guy (white guy) and I believe I am falling in love. But I have not yet ended my relationship with my partner. What should I do? I went out on a date with this amazing white guy and we ended up HAVING SEX on the public park. For so long I felt so lonely and its just happen. I feel bad because I cheated on my partner; but he cheated on me first. And its not revenge or anything it just happen. To my surprise this white guy told me he wants to take it slow, but I mean we already had sex! Now we suppose to take it slow. He was really sweet and I don’t know, I felt butterflies inside my stomach. I think I really like him.
Do you guys think the white guy really wants something serious later on? Or he was just looking for sex? I am so confuse? Should I tell my partner what happen? Or should I just stay quite and stay with my partner? Or should I risk it and leave him?…but what if the white guy doesn’t want anything serious?