Just dont know what happened with us?

so i told my friend that I like her like way bak in October, but i never asked her out cuz i didnt have the guts. When i told her, she was like "aww i knew it." And from then on we've just been getting really close. Problem is that she just got a boyfriend recently, but when he's not around im always making her laff and she flirts alot with me too. u think i should stick with her and wait till she breaks up with him? it makes me angry too cuz she wears HIS jacket during cl......