I need relationship advice?

ok my friend has a girlfriend and i have loved her for a long time, by the way we are at the end of our sophmore year, and i know that she will never liked me whatsoever especially because she is deeply in love with my friend and it is likewise the other way. I accidentally sent my friend a text saying how i felt about her like her eyes are so beautiful that everytime i look into them i melt and stuff like that it was completely by accident and he already knew that i loved her pionatly. Now he is very angry with me and i dont know what to do i didnt see any reason for him to be mad at me i mean i hate myself for even feeling that way about his girlfriend but seriously he shouldnt be mad at me he is my best friend. what should i do?