Unhealthy relationship. what should i do please help?

I have completed my master's degree and now I am free this is why I am more hurt than normal. We met in the university and became group fellows. After some time I expressed my feelings to her but she refused saying you are like all other friends but I Showed her that I am not hurt with this. Then it continued but her behavior changed a bit in my favor. Then we started talking on phone for study purposes. And then it continued. She was moving slowly in the relationship and I was satisfied. Our relation grew and there came time when she demanded all the time for her. She became possessive and didn't let me spend time with my friends or other things but as I always enjoyed her company I accepted this. We were like talking on the phone all the day and when we were not we were together in the university. I mean we were together all the time but I enjoyed her company sometimes I felt it as a burden because she won't let me hangout with friends but I don't know why I accepted this and left all of my interests for her even I left my internet business to spend more time with her (internet business was at initial stage like I had some websites but it didn't start paying me off but it was a big deal for me) she belonged to some other religious sect but kept it hidden from me according to her it was not important. Once I offended that sect and she told me that she belonged to it. She said that these things should not come in the relationship we had a little fight but things settled. After that she expressed that she view me as very liberal but I was not up to her expectations and her behavior kept on changing and she start fighting with me on little issues. I was so much involved with her but all that romance from her kept on declining and time came when she just argued nothing else. She used to kiss me through phone hundreds of times a day and it all vanished. So I asked her what on she said I can't forget what you said about my sect so give me time I will heal. I gave her a month but nothing good happened her behavior got worse than ever. So I thought it never going to be good again so I said to her that we should not continue now. She insisted not to do that but I did. Then she said ok. After a few days I started missing her so badly that I didn't find anything in this world to heal me. All of my friends kept on asking how it's going with her as they didn't know about the break up and it kept on reminding. After I got helpless I got my friend involved in this matter and asked her to reunite. She said I would talk but nothing like before will happen again. After this due to her behavior I fought with her many times and said I won't work but always reunited again as I am unable to live without her. Not the last patch up was made 2 months before and there is nothing but fights and arguments. She promised 1 month ago that she would not be rude to me or ignore me but she always pin points any negative thing or word which is spoken by me. For instance if I say to her that you are not talking to me in a good way she says you are never happy with me. And if I prepare my mind to move on she shows me her nice side and asks can't you wait for some time to make everything good. If I agree with this and come to her again she becomes rude again. If I don't contact her she asks why are you so BZ that you even don't contact me or message me and if I start messaging her she willingly replies late or ignores? I don't understand what I want. I mean if I think to leave her I see myself in a worse condition being all alone. Going to friends and family don't work now my heart just needs her company. So what should I do? I know my English is not so good so pardon.