My brother's best friend likes me

My brother's best friend

About a year ago I started making friends with my brother's best friend. He had my number, we texted a lot and whenever we saw each other there was more than friendship in the air. Still nothing worked, probably because he was afraid of losing my brother as a result. At some point I “gave up” and we didn't have that much contact. About half a year ago we met on a birthday (my brother was there too) and he was trying all the time to “clear up” a girl, which he always tries because he is rather insecure and something new would like to see his ex. Of course, I was totally angry somewhere ... and well there was another very good friend of my brother's who probably thought I was pretty good. I had something with him, but I think at first it was just to make your best friend jealous. I then had a lot of contact with said good friend and began to like him a lot. But a few months ago we broke up because it was going to be a long-distance relationship and he didn't want that. He hurt me a lot because of that (and other things too) and I'm still a little sad to this day. The friendship with my brother has also deteriorated a lot since I told my brother how ass he was towards me.
Well, now I've been back in touch with his best friend lately. We went to a party yesterday and he was totally drunk and said how perfect I was. In all his confusion he said that the two of us could never have anything, since my brother is his best friend. But he still questioned that, "right?" , "Is not it?".
Then he was looking for a girl again, and in the end he had something with a fellow student of mine.
So, and that's the point. I was totally jealous and in total emotional chaos. I'm actually still attached to my ex, even though I wonder if the only time I got together with him was to suppress feelings of being a best friend. Should I tell my best friend what I am feeling, or that I don't know exactly what I am feeling, but that it bothers me that he had something with someone else? I mean, jealousy always has to do with feelings, doesn't it? Or should I leave it because otherwise I might destroy this friendship with my brother too? I can't just grab my brother's friends ... but I'm also afraid that he will start something solid with the fellow student and then I will notice how much he means to me, which I may not know yet.

Thanks for reading, I just wanted to write this off my heart.