Relationships

I have no idea what to do about my romantic life?

Ok so my mom has this friend and our families have know each other for years and she has 4 kids as well as my parents, but anyways two of her sons are around my age, me being 18, son1 being 20 and son2 being 18 as well.

So to start of i have known the both of them since we were like 7-9 years old and our families are close to a good enough extent but not like too close, and so around this time last year I started hanging out more with the son that is my age (son2) because I have been in online school since my sophomore year and so he invited me to go to prom with him just incase I didn't go back to school (we didn't end up going because he got in trouble) hopefully I go this year though, but anyways we started hanging out more and getting closer and I thought it was good because I don't have many friends besides like 2 people being in online school. But he ended up liking me and at the time i could not reciprocate those feelings because i thought he was too immature and I only saw him as a friend, so when he confessed to me I told him how i felt because i personally think u should always tell someone how you feel rather than leading them on.

But anyways he didn't get super rude about me not liking him back but we sorta got distanced for a while and then we slowly started talking again. Now skipping some time ahead from his confession my family and I went over their house for something and a week before that my mom mentioned something about him having a girlfriend and I rlly didn't care, because like i said i didn't like him that way. So we went to there house and I saw him for the slightest bit and he looked really good tbh (I mean he had before but like i said his immaturity was a big turn off for me) but a few hours later his girlfriend came over she was sweet and we said a brief hi and he went to another space to hang out with her.

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(the rest...)
Once I got home that night i really started contemplating my feelings for him, and he just seemed different from when we last saw each other which was like maybe 4-5 months back from that day.

And then i realized I had feelings for him. after a few weeks of not seeing him we had planned to hang out and i thought i was over my crush and it was just something brief, but when I saw him and actually spent time with him i realized it wasn't a small crush and I really liked him... but
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ofc he had a girlfriend. but there was still so much tension when we hung out and i had such a great time, once i left their house i wanted to see him again soon and luckily i did a few weeks later on my 18th bday for a dinner party, my best friend ofc was their and they knew how i felt about him so they had me switch seats and sit next to him and we talked about and it was hot and cold
I have no idea what to do about my romantic life?
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