I slept with a younger guy and he's ignoring me, should I try to talk to him?

Anonymous
Hi, please don't be rude about my question, I'm going to try to make it short but it's confusing without all the details, I'm 28 and I slept with an 18 year old, his sister has been with my cousin for nearly 5 years now, and it's always been us 3 to hang out and do things together, he wanted to talk to me when he first saw me when his sister came to my house to see her boyfriend but he was too young, he started flirting with me after that, trying to get me to sleep with him when he was 16, he doesn't have a phone with service on it, but when he does get online he hits on a lot of girls, when he gets or doesn't get what he wants out of them he un friends them and blocks them, we all 3 went out a few days ago and got a room and I was a little tipsy, we had all been drinking, he was really drunk and I went up to him and tried to talk to him, he's never said much to me except when his sisters asked him if he likes me he said he considers me like family, but this night he kissed me and we had sex, after he tried to get a friend of his to pick him up and get him something to eat, he ended up staying there because he couldn't come get him, well, I just saw where he blocked me on Facebook today and he's been ignoring me, not joking around trying to make me laugh like he usually does, I've asked his step brother if he likes me and he said he doesn't know, i want to talk to him but I don't know what to say or if I would mess up by saying something to him, every time I see him he's always bragging about all of the girls yhsts trying to talk to him, today he mentioned his friends sister grabbed his butt and his junk when he stayed the night there but he says he considers her a sister, I'm confused, I want to apologize because I feel like I made him do something he didn't want to, he won't even look at me, he said he doesn't remember anything that happened that night, what should I do, I'm sorry this is so long
Updates
+1 y
I know, I should have seen it coming but I didn't know how he really was until his family told me, I guess he likes me and a few other girls too
I slept with a younger guy and he's ignoring me, should I try to talk to him?
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