advice???

k so this guy i really like, actually love, told me he loved me to, he had a girlfriend at this time, so for three months we hung out and got close, i opened up and told him everything. he told me that he was breaking up with his girlfriend but he also wanted to start over and he wanted to be single for a while, five days ago i found he is dating my friend who knows how i feel about him. and now i don't know what to do, i'm a little mad at both of them cause they never told me anything..