girlfriend keeps talking to ex/best friend.

girlfriend keeps talking to ex/best friend.
I know im being stupid about this but Im very confussed. Ill make this short.
met this girl at work who told me was interested in going out with me. I like her, shes always been very nice and cute.
She tells me shes getting divorced that the husband left her shortly after getting married cause of work and they kind of rushed getting married after dating a few months.
She told me that since they have been in the process of getting divorced she was dating this other guy at work but things were not working out since the guy already has a girlfriend...and an ex with his son...so shes kind of the 3rd wheel and is tired of that so she's moving on.
I didnt make a big deal of it and continued dating her, things were great and we were getting a long and having good times together. 2 months later i get a call from the husband and tells me they were never getting divorced and wants to know whats going on. anyway all 3 of us ended up meeting up to settle this like grown ups. we talked and that's when the husband realized she had not only cheated on him with me but also that other guy...that also happens to be her best friend.
The husband dumps her and she begs me to stay with her ....i did..im in love with her.
we continue dating and i keep having issues with her talking with her best friend...she tells me she loves me and not to worry but i keep hearing rumors and they are still hooking up...she denies everything of course.
so 2 months go by since all this happens and we talk to each other and promise to work on our relationship, we have a great valentines and i give her a ring to symbolize our relationship. she promises me the sky and the moon we move in together and then i find out shes talking to some other guy...goes as far as saving him on her phone under a girls name....i confronted her over it, she lies and tells me is an old friend from school. I later find out she met him at work on a temporary assignment. Again she promised me to stop talking to him and work on us. we've been together 4 months since moving in together and i bumped into her best friend who tells me im being an a hole and that she had sex with him 1 week after valentines and im just stupid that she loves him but he has no interest on her that shes just a friend with benefits to him. I confronted her about this and she told me it was all lies........then after a 2 hour conversation she told me it was true that she was con fussed when it happened, that she had sex with him. Anyway, i dumped her....she kept begging me back and since i love her and i knew she had not done anything behind my back since we moved in together i took her back and told her never ever to talk to this guy. she told me she would never see him again. Just found out 2 days ago she goes to were he works to see him and have lunch with him from time to time, i asked her today about it. she said it was lies, then she tells me that "ok, its true but is not like that anymore, we are just friends" Ive asked her like 50 times to stop talking to this guy and she keeps on doing it. im done, i broke up with her and asked her to leave. her family showed up and picked up her stuff. she keep calling me telling me that she loves me and wants to come home.....i love her...im hurt...i cant keep checking on her all the time....what should i do?

Break up with her and don't contact her, or respond to any contact she initiates. In time you'll hurt less. She can only make promises so many times before they're worthless, and it sounds like she'll never really stop talking to this other guy or meeting up with him, etc.

You cant turn a whore into a house wife.

she does not respect you, get away from her. she is toxic!
she will keep doing this and allways have an excuse, she knows your a VERY tolerant person and
that you love her. and when she knows this she can manipulate you into being the sucker she wants you to be; a voluntary victim.