My Girlfriend Cheated me

I have a relationship with my girlfriend approx 11 months. Her mother has a breast cancer & she has no father.She took 1 month for saying yes to me so she knows her family situation & when i asked to her if ur family will don't allow us for marriage what will u do?she said i will go with u & she makes me more & more promises for our future.But from last 15 days suddenly she told me that she can't marry with me cuz her mother don't allow her & one thing more my parents already met with her mother after 1 month relation & they decide our marriage aftr 2 years.But suddenly she told me that her mother creates problem with her she toned her always that do whatever u want to do,than dont come here.I don't know y & she said she can't marry with me because she has to take care of her home. So my concern is before start of relation she know all the situation after she said yes to me & she promised me that she will control everything i dont need take panic of our future & now her mother & she playing with me & my family.Whenever me & my family ask the reason they have silly ans & her daughter is react like that she is not interested cuz mother not allowing. If she knows everything so y she promised me & she shows like we have a future of marriage.She cheats me & now she is answering me,she played with my feelings after she knows that how much i love her & I can't leave without her.There is no physical relation b/s us but we have our chats/pics & witnesses which can prove she always says we got marriage & relationship is running with my & her permission,& we are happy together.. now I can't live without her.i want to live with her if she wants or not cuz She believes me that she is my wife & i am her husband. There is any law which can help me.