Help for my ending relationship

I am 22yrs old men and I hv got a girl friend and it's been just 2 months since we have been together and she is so friendly and hv alot of friends that are men. and I am okay with that but here is the thing there is some guy who's rich and he wanted her and he becomes a friend of her men friends and they took her to a place where he chill and after some times he offered money for her for one night stand and she told me and I told her to be far from him and do not even meet him and I went to another place and one day he went to her work place and take her out after work and she was not answering my texts almost for all night and she told me that she was unable to touch her phone because they made her busy. after 2 weeks she told to every body that her uncle sent 2000 euro for her to buy a phone for her self and she kept this as a secret from her brother because he will get jealous of this, and on the next day her friends asked her to text him and he will take everybody out and she texted him to do so and he did and she didn't told me that she called him I thought he just informed from one of her friends but she was the one who texted him to come and join them. I was mad on her I told her to send me all the chats with him and she said she don't want to do this in case of privacy, and I told her that I can't be with her even though i love her and she is telling me she didn't do any thing and she did all those things because she is a good hearted person and she swear for me and now I am lost I need your help guys