I seriously don't know what to do with her!

I met a girl around my ages on fb last year, we begin to chat with each others till we get into relationships in 3 months time. We both love each others, but slowly she told me that she was marriage and had been staying with her husband for 2 years! She told me that she didn't love him because the reason why she marriage him was because the man are able to provides her shelter and living needs only. I was really shocked when she told me this, but i kept this for secret for her. I used to think that i should broke up with her because i dislike being third party! But she keeps telling me i could provide love to her, i seriously don't know what to do, so i keep in touch with her and kept our relationship as secret, i love her as my gf despite i know all this truth. Slowly after 3 months she asks to broke up with me, i thought this is the best way for her to realise she should continue love her husband instead for finding love outside. But after a while, she told me she was in relationship with other man outside again! I was so disappointed to her, when i ask her why, she told me she needs love so much till she doesn't mind to find another man outside in order to seek for love. I continue asking her why she doesnt want to tell your current husband that u don't love him and get divorce in order to set free yourself to find true love? She constantly says that if she divorce she can't have so many money and good shelter anymore, in the other word, she prefer to have a secret relationship outside with other man despite she is marriage. For so many times, she gives so many excuses like she has mental illness, lack of money, love to all her mistakes she made, i seriously dont know what to do, i promised her i will always be her friend to support her, and if i scold her again about her mistakes our friendship will gone, so i still always support her when she depressed. She also used to lied to me, push all her mistakes to me and let other people blame me instead, all these i can forgive her because she is scares of people blaming on her and hates her and she wants me to bear for her, so i bear her mistakes and said that was my mistakes, people could hates me instead. I understand she has mental illness, more blaming from other people will makes her more suicidal, so i decided to protect her. At the end, i get more people who dislike and hates me because of her, and she is still so happy with her life. I love her, although we are only friend, I really really wanted to tell her that i am really enough! She keeps use me as shield for all her mistakes and yet tells me we will go through all these together which is actually just want me to bear all! But i am so soft-heart to tell her, so i keep my friendship with her. I really feel like i am a fool, a tool for her, seriously she wont even bother to talk to me when in a chat, i am the one who often talk to her first, she only find me when she needs help! that's all. She has only guy friends! many of them, i often remind her be careful of guys, but she won't listen and keep "dating" different guy every week for outing, then she told me im too boring that's why she wanna find many others guys to make her happy! I admit, i am sucks in joking and humor =( but i always be there for her when she needs help, Her husband didn't even know she dated so many guys, and she even lied to her husband. I felt so sorry for her husband, really. She said she lost hopes to find a female friend, only guy friend she trusts, she said. Right now, im tutoring her college revision for free so that she could pass her exam next month, but everytime we meet up, she spent most of the time texting and calling other guy friend, focus only a little on my tutoring and revision, when i ask, she said hey i thought you always support me from whatever i do, even calling other guy friend to chitchat! You are just to help me tutoring. I treated her as my best friend, i felt like i am a stranger for her! And now, i don't know what to do anymore, i kept swallowed my emotions alone at home, she is my only best friend but i just can't tell her, all she will says is sorry sorry and repeat the same mistake all over again! I cherish her as my best friend, but she did all these to me, should i just broke this friendship and leave her alone? or continue to support her as best friend? I'm really enough! I need helps!!!! I can't stand this anymore! I am really sad when i see her finding others guys and did the same thing over and over again! And i am just a tool for her! treat me like a stranger! Why am i still her friend!

stop the nonsense! grow a pair! You're being a fool, a doormat if you don't break this off! If you continue this relationship it says you have no self respect. Cut all communications! Cut the friendship that's the hook that keeps you in this mess. I believe you know what you need to do, so do. MOVE ON you can do better...