How do you get over betrayal?

i know this guy liked me and i liked him too, but his best friend also liked me. i couldn't go out with him, as i know it would hurt his friend, as he had also recently told me he liked me. after a week or so, my best friend told me she also had feelings for the guy i liked, and i decided not to tell her he liked me, as i was scared it would break her heart. so this guy asked me out, and thinking i was being a good friend, i said no, even though i really wanted to. after that, i didn't talk to him as much as i could as i was in a difficult situation, as i knew that the more i talked to him, the more i would like him, making it so much harder for me to say no. at this point, pretty much everybody, including my best friend, knew we liked each other. but she stuck by, and carried on liking him, and i knew they were getting closer and closer. i was struggling to keep him, but i knew the only way was to ask him out, and i couldn't do that to my best friend. a few weeks later, they got together. i was heart broken, not only because i liked him, but because it was hard for me to deal with both the betrayal from my best friend, and the betrayal from him, as he knew i couldn't go out with him because of her. I'm trying to be happy for her, but it's so hard. i know i should've spoken to them both around the time, but it is it too late to speak to him about it now? it's been a month or so, and i'm still finding it hard to get over it. is this just me being stupid or do i have every right to feel betrayed?