Need advice with a boy

So I've known this boy I like for about 5 years and I remember him telling me from the moment he saw me he thought I was the prettiest girl he'd ever seen. I made him tell me that every single day for 2 years. Since we've met we've always been more than friends and we've always had an emotional connection but never really started dating. He's one of my brothers friends (my brothers 2 years older than me and he's 1 year older than me) and we stayed up and talked to each other from 1-4 in the morning and about a week ago he was at my house and tried to kiss me but I pushed him away because I didn't want it to get awkward and this big thing happened with some other girl and he asked her for nudes and she sent them and asked for them in return etc. (that was after I pushed him away when he tried to kiss me) and now he has a girlfriend and I can't help it but I'm jealous because I thought he liked me and was going to wait for me and whatever and I honestly think I love him because I've never cared about someone this deeply before I don't want to say it's love but taken everything into consideration I honestly believe I'm in love with him I don't know what to do or how to tell him how I feel and even if I should tell him. My dad used to make fun of me and joke about how we were going to end up married and I never believed him until now I can see myself marrying him and spending the rest of my life with him and that's hard to say bc I don't want to get too attached and get hurt but he's never been anything less than a gentleman to me he's always so sweet and polite and very flirty but I don't know what to do..... I don't have any older sisters and I feel uncomfortable talking to my brother.....advice?