Help RELATIONSHIP PROBLEMS!!!!!?

so i new my girl for 4 years. basically been together since then. but it was long distance. and we were completly in love. we always had a date that is coming up when we the distance between us would close and we would finally be together. but on the fourth year, which was earlier this year, she ****** around and cheated. my heart dropped cuz she was pregnant by that guy. i was heated. and torn at the same time, me n her were so close, and then she changed and did that. so when i found out she begged me not to leave her and even got an abortion just to show that she made a horrible mistake and wanted to stay with me. ok, so days and weeks go on and she seems like shes real commited to try and make this work again, but then she cheated again, then even gets a whole nother relationship on the side. i was like omg wtf! but it was long distance and i saw her when i could, but these guys lived close to her so they had me beat on that. so eventually in june she got a bf. an they been together ever since. i never really left the picture i been hittn her up periodically sayn that i love her an tryna talk with her. but she didnt really want to hear it out. there would be some times were she would here it out, but for the most part it fell on def ears. so about a month and a half ago i send her a text saying that im going to let her go and not be in her life anymore. she texted me back and wrote just no that i will always miss and love you. so time goes on, and she actually starts calling me, but i ignore her calls. i ignored all contact. she still has her boyfriend during the calls btw. she called for about a month, and ignored them all. then i bought her a christmas present and sent it to her. she called me when she got it, but i didnt answer. i could tell she was missing me like crazy. so then i finally picked up, and she was basically telling me that she misses me, and asking me what if i want you back and all that stuff. but i new that i couldnt do anything because it would still be long distance and she still has that boyfriend. they break up and get back together almost every week btw. she cried to me sayn that she never should have done wat she did to me, and that if she was actually here with me then it would have never happened. an saying that she loves me. then i told her i have a girlfriend. (when i really dont) and she couldnt believe it. an basically said that she would wait forever for me. so then a two weeks go by, weve spoken a few times during the 2 weeks. she called me yesterday saying that her and her boyfriend broke up. i asked her if she loves me and she said yea. but then today her an her boyfriend got back together because he knows that im talking to her again an hes feeling threatened. the problem is that i want her back. and everything i have done is a plan to get her back and marry her. i no she did stupid **** before and a part of me wants to crack her head. but the other part is just so inlove with her. just like i no she still loves me. but i cant tell her i want her back just yet cuz the distance would just kill everything again. iwas going to go to her and tell her on her bday which is in march. i no she would be excited if she saw me show up, an i would ask her to marry me to put an end to this mess. because this summer coming up is basically the time we had set to actually be together. but i no shes still with this guy, and i dont want her to get to attatched to him, to the point were im not anything to her anymore. waiting for march feels so long. its 9 weeks from now. idk if i should go tel her before that or stick to march. because if i stick to march then its only another 8 weeks before were going to be together. but i just dont want her to attacthed to him. i mean she says she loves him and all that ****. but. i love her. and you only live once. and i want her to be mine. like we have planned for 4 years. this is the time we had set so ima go for it. i hope i dont fall on my face. waiting for march hurts alot. should i go before march or no? if i go befor march itll go back to long distance for another few weeks tho...help!