Is the sexual assault?

So when I was younger we had lots of friends over at our house all the time girls and guys. I do not remember how old I was around this time but I am old enough to remember everything that happened like it was yesterday. So one day we were all playing hide and seek, my brothers friend is much older maybe 24 or 25 now. I am now 20. So everyone went downstairs and he was left upstairs with me. he tapped me and we got under the covers and I’m thinking we are playing hide and seek still but this is sexual. Me not knowing any better I was allowing him to do these things but at the time I am really young. Not even knowing about sex because my parents never introduced me to that yet. I remember him touching me and he told me to take off my clothes. I took off my bottoms and he tried to put his penis inside of me. I was allowing this to happen like I said but I didn’t know any better I wasn’t aware of what was actually going on on a serious note please don’t say “well I think you’d know if someone was being sexual with you” not everyone is introduced to those things early. So he proceeded to try to get it in but someone came upstairs and he hurried and stopped. It never happened but it seems as if i were just saved by that happening. It’s been years and it’s bothering me that it was my brothers friend. I’ve never told anyone not a single person this has happened. It’s like when I see him, It’s just awkward. Now that I have grown up and I understand sex etc I’m figuring he tried to sexually assault me? Let’s be honest it would have happened if no one came up the stairs. Although I was allowing it I had no clue that sex was actually gonna be happening. I didn’t even know about a period when I got one for God’s sake. I was so young and uneducated. Can someone help me understand what this was? I never speak on it and I never plan on doing so either