I’m not sure who I should talk to about this and I am so confused.

Let me begin at the start. So about 3 years back l moved across the country and left my whole life behind (I was ten-ish at the time) but my parents friend was having his 50th let’s call him Jim and I was begging to go back to see all my old friends so of course we brought plane tickets and planned to go over there after Christmas. When l got there l met some of my friends and some of them I didn’t even get along with which was not the best feeling. Later on I went and stayed with Jim and his wife Maddie (I was very close to maddie she was like a second mother to me) anyway she had 3 boys (all much older than me). The middle boy let’s call him Hunter was about 10-ish year older than me. The first time I saw him (when we where on the trip) was the day before the party and 2 days before we went home. Anyway it was great seeing him but he didn’t respect my privacy and just walked into the room I was staying in. The next day (the day of the party)he started slapping me on the butt, he still disrespected my privacy and kept following me and stuff. I was supposed to greet everyone at the party and give them a tour around the party showing where the toilette was and the food and everything but while I was waiting for the guests he kept coming to me and saying hi. After all the guests arrived I didn’t feel so well so I decided to go upstairs and lay down a couple hours later Hunter came up he asked why I was upstairs and I told him that I was not feeling well. Then out of the blue he started talking about relationship and boyfriends and if I wanted a boyfriend then he started to lean forward like he was gonna kiss me. I moved to the other side of the bed and said I was going downstairs to get food then I ran downstairs and locked myself in the bathroom trying to make sense of what happened. Why has he leaning forward and did he try to kiss me. Besides my young age of 13 many people think I’m graduated high school. I can see why I’m very tall. Taller than many adults I know. Anyway when I though hunter went back to the party I went upstairs and put my shoes on and headed to the party. I stayed with my parents most of the time and avoided Hunter. Everyone at the party that was over 18 was very drunk accept a few people like my parents. Later on at the party I didn’t know where my parents were so I sat with some ladies. After I sat down Hunter walked over and sat on my lap. Crushed from the weight of him I pushed him off to the chair next to me trying not to make a scene. After that I made sure that he wouldn’t come near me as I was uncomfortable about his behaviour. I didn’t know what I should do. I am home now and I probably won’t see him until the marriage of this big brother (if I get invited) or the next time we visit in a couple years. I didn’t make a scene and get up at him when he was making my uncomfortable with his behaviour because that would destroy my friendship with Maddie and I don’t know if I should talk about this with my parents because they will find out that it is Hunter one way or another and it will destroy friendships with people.

I need your help please