dump this girl.
had the same expirience.
me and my girl were together for almost a year. her ex came back from to town, he failed at his new job.
after that they met secretly and she came to me and was crying and told me, she didnt know, how to feel about him.
i tried to not think about it, but after that things werent the same.
she was always talking about her ex and met him now and then, then i had to dump her, because i couldnt trust her anymore.
after two weeks they got together and the guy dumped her again after 1 month.
all this drama for nothing. i would just recommand you, dont let it get that far, it could get really heavy and you both will get hurt,
especially u.