Should I Keep On Dating This Girl Or Should I Break Up With Her?

I got to meet a girl through facebook, we talked and finally hooked up, i asked her out and she accepted, she told me about her two boyfriends that left her for greener pasture, one left for italy and the other one went to ghana, she never broke up with any of them.

So we started dating as we both are student in the same school and department. The whole relationship grew into deep love and affection between us, but she still talk on phone with her previous boyfriends, even when we are together, she will be engaged in a long conversation on phone with her previous boyfriend and also on whatsapp, it got to a stage that i saw a message she sent to her previous boyfriend in ghana that she love him so much, i got so angry with her and she begged me, & she confess that she still love him but she loves me the most and she would love to marry me, we settled the issue.

And now the boyfriend in ghana paid her a surprise visit yesterday when i was at her place and was about leaving, with this now, should i still continue dating her or not? bearing in mind that she is so supportive of me in school.