I'm in love with this girl who is in love with another guy

So i fell in love with this girl who is straight(i am a bisexual).Initially we were friends but later i couldn't hide my feelings and i confronted her.I told her that i can't be friends with her coz i feel something for her.She loved me too and didn't wanna lose me so she said yes.But our families won't accept this that's why we decided to stay together but get married to diff guys.She told me that she doesn't wanna lose me so she won't get married coz that will drift as apart.But i somehow convinced her and literally forced her to start seeing guys.Then comes this guy who i hate like hell and he's in love with my girl.They work at the same place which is why they get to spend more time together.Few days back she told me that she likes him a lot and wants to give him a chance.A part of me wants to see her happy and would do whatever it takes to make her happy even if that means to let her go be with someone else.But then a part of me also gets hurt when i see her with someone else.Not a day goes by when we don't fight over this guy.I told her that i don't like him so now she's like she won't talk to him coz i am and will always be her priority but she asked me to give her some time to get over him coz she felt like she was falling for him. Sometimes i feel like i am being selfish and i should let her be happy with that guy.But i can't see her with someone else,it kills me from inside. I'm so confused i don't know what to do.The fact that she fell for someone else is breaking my heart into pieces and all of this(they talk on call,text,meet) is happening right in front of my eyes.I was the one who forced her so i can't blame her either.pls tell me what should i do?