I need some advice...

More like I need help idk how to deal with this.

I think I'm falling in love with my best friend but my best friend is like my second world cause my family always comes first.
He is kind and sweet, he never gets mad at me even though I get mad at him sometimes, he always go places with me whenever he is free and no matter how mean I get or how bad I do things he is literally always by my side.

He once asked me if I wanted to go out on Valentine's Day (omg I said no) he said it was our "date", I noticed that he gets mad when I talk about other guys but I always reassure him that I like him way more than any other person.

Lately I keep thinking about him, I know it's wrong cause I'm sure that falling in love with him is not the right thing to do and we both have had someone in the past, now it's been almost 2 and half years that we r single.

I don't wanna like him that way but whenever I think that one day he will get married I get so frustrated. I wish I could confess but I'll get rejected (probably) idk what to do, idk what to think and I'm so fucking scared of falling head over heels for him and he falls for someone else.

What shall I do, what can I do.... Idk....