My vry vry low self-esteem?

Hi there im 22yrs old....im a guy who vry vry concern about the look of myself...i got a quite good looking face.....but 1 thing that bring me down always is my body...bcasue its look so horrible for me and i cant accept it, whenever i look infront of the mirror i juz feel vry sad !! My rib bone looks so diffrent from others, and im skinny ..i just dont dare to take off my shirt ..this caused me lost a lot of good friend of mine...and lots of opportunity that i can do in this world ! and i mssed out alot of good chances !!...im so sad when my friend talks about their gf ...or had with hw many girls..or talk about swimming, or ask me out for mage or spa ...i will juz keep quite or sneak off..tis make me lost alot of gd friend.......i juz couldn't alow myself to join them and the conversation .tats y i couldnt hav long term realationship with my friends..im always vry vry sad when comes to this stage ..and i feels that it affects my LIFE ! if i dont overcome it ..!!! i want to live normal !........and i dont wan this to happend anymore !!..what should i do...... ....